Integra DRX-8.4 Multichannel Receiver: Overview, features, build, a few pre-out measurements...

Obviously, value is an important consideration for consumers when it comes to buying and enjoying products. As discussed over the years, I'm not an audiophile who's particularly interested in the luxury aspect of these machines. To me, the ideal of achieving "high fidelity" sound does not care about MSRP or some other determinant of whether a product is artificially exotic/elite, thus "High End Audio" (a.k.a. High Priced Audio) is meaningless to me unless there is evidence of improved sonic performance (whether from plain increased objective fidelity or incorporating technical features) correlating with higher asking price. As such, I believe audiophiles should seriously think about the value of modern AV receivers which over time have also incrementally shown improved sound quality by incorporating higher quality DACs, newer DSP room correction technologies, and potential benefits like balanced connections.

In my opinion, this also means the divide between "home theater" enthusiasts and "audiophiles" is largely artificial when it comes to sonic performance. Subjectively, we're all aiming for an excellent audio experience with high-fidelity to the source with utmost clarity (including time-domain coherence), low distortion, high dynamic range, excellent reproduction of nuances, while achieving realistic/intended soundstage. Objectively, a high quality AV receiver these days should not have difficulty providing hi-fi performance compared to many very expensive products (like the Dan D'Agostino Momentum monoblocks US$80k/pr as an obvious example - other than high power, there's nothing particularly good), plus typically these AV companies provide way more features and modern amenities. The R&D firepower behind these companies are substantial compared to the small-business shops that typically make products for the esoteric 2-channel audiophile niche. Over time, as I hope audiophiles increasingly consider enjoying the new multichannel recordings and remixes, moving into "immersive" audio, these multichannel receivers should be seen as serious options.

The only utilitarian difference between home theater enthusiasts and audiophiles is whether video playback is needed.

In this post, let's start with having a look at the item pictured above, the Integra DRX-8.4 multichannel receiver. (Discussions and measurements of AV receivers are not new on this blog with previous posts on the Yamaha RX-V781 and Onkyo TX-NR1009.)

Despite being the current flagship receiver from Integra, the price is "only" US$3,200 or about CAD$4,000. I bought this item through standard retail channels online because I was interested in it; no company incentives.

You might not be familiar with the Integra brand name since these units are less easily accessible to end-users because this division of Onkyo caters to the home theater integrator market - folks who are more likely to be attending CEDIA Expo than Munich/Vienna High End.

[In the world of AV audio products, many of the brands are under the same holding company: D&M Holdings owns Denon, Marantz, Polk whereas Voxx International is the major holder along with Sharp Corporation under the name Premium Audio Company (PAC) with Klipsh, Onkyo, Integra, Pioneer, Jamo, Energy among its stable of companies.] 

The receiver came well-packed, double-boxed, with accessories in that white Integra upper package when you open it up. Inside are the usual contents with some pamphlets, warranty info (3 years parts & labor new), Dirac Live Bass Control leaflet, AM and FM antennae (might not use since integrated TuneIn internet radio works well), thick 14AWG power cable, room calibration mic (in pink bag), and the remote control which is of reasonable quality, plastic, backlit keys, with Panasonic batteries included (it's a good sign when recognizable brand name batteries are included, right?!).

Made in Malaysia. 7 HDMI inputs (6 rear + 1 front), 3 HDMI outputs (HDMI 1 can be set to "Discrete Audio Path Mode"). Moving magnet phono input. Ethernet is typical 10/100Mbps. 2 Coaxial digital inputs, 3 TosLink optical inputs. 4 RCA line inputs. Legacy video inputs: 1 component, 2 composite. Single stereo XLR input (high quality DAC). XLR pre-outs for front stereo + center channel + 2 subwoofers. Miscellaneous: RS232 serial port, various 12V trigger in/out and IR in.

While most of the rear connections should be familiar to anyone who has used a more powerful AV receiver over the years, notice the inclusion of XLR balanced audio ports. Assuming the device is able to achieve good low-noise performance (which we'll measure later), this is a nice feature for 2-channel audiophiles who have high resolution DACs with balanced out. In practice, balanced cabling is most useful if you're placing your DAC, amps and subs further away requiring longer interconnects to reduce interference.

Pre-out RCA impedance is specified as 470Ω and XLR output impedance 220Ω.

Currently there are not many reasonably-priced receivers around this price point with XLR capability. For example, the Yamaha RX-A6A (US$2150, 9.2Ch), Yamaha RX-A8A (US$2900, 11.2Ch) and Pioneer Elite VSX LX805 (US$2000, 11.4Ch) support 2-channel XLR in and front stereo balanced pre-outs. I like that the Integra has center channel pre-out also which IMO is just as important as the front stereo pair when doing multichannel (with vocals anchored to the center) and for the subs. Beyond this, I think we're looking at much more expensive separate multichannel processors like the monster Marantz AV 10 15.4 channel (US$7k, plus you'll need to buy something like the matching 16-channel AMP 10 also US$7k based on Class D ICEedge modules), then there are the StormAudio and Trinnov products typically well beyond US$10k.

Since the Integra caters to the custom installation market, it does have a few extra features one might not see in other AV receivers. All settings can be accessed through the front display and controls along with full-featured web-based set-up page as well. Little things like the rear panel as shown above uses black text on white background scheme to improve contrast when installing in dark, cramped spaces. It also is compatible with remote monitoring platforms like OvrC Pro, Domotz, Luxul ProWatch - I have no idea what this stuff is 🙂. We've also got Alexa, Google and Josh.ai smart home assistant compatibility. Then there are all the remote control systems like Control4, Crestron, URC Automation, ELAN, and RTI this can be paired with.

The convenient web interface also has a "toolkit" to run various HDMI diagnostics. The quad-core "network processor" feels responsive. To access the web interface, enter the receiver's IP address on your browser, login and password defaults are "ciuser":

Simple 2.0 speaker set-up shown. For folks who like tweaking minutiae, there are
settings here to change the DAC filter ("Sharp" is good) and 2x/4x internal upsampling.
Seriously, I have never seen this level of overwhelming customizability in any
other device on a single settings page!

There's also the Integra Control Pro Android/iOS app to adjust some of the more essential features and to run Dirac Live:

The unit is a hefty 50lbs, with dimensions of around 17" wide x 18" deep x 8" high. Given that there are 11 linear Class AB amplifier channels inside (advertised as 150Wpc into 8Ω, 0.08% THD 2-channels driven; should have no problem hitting 300Wpc into 4Ω), make sure to give this unit space to dissipate heat. Having said this, in daily use at normal volumes with multichannel content, I've found that this receiver runs comparatively cooler than most of my previous receivers.

Here's a little video tour for those who like videos: 😉

A look under the chassis from Polish review.

As far as I can tell, there are 4 fans in this unit. There is one on top that spins up in normal use (as shown in the video) and is quiet, inaudible in my sound room at the seating position except on the quietest of late evenings. The other top fan turns on briefly when starting (depending on how you set the sleep options), when running the initial set-up or when upgrading the firmware. If we look below, there are 2 other fans for amplifier cooling, so far I can't say I've heard them turn on in use running my 5.2.2 system in cool ambient temperature this time of the year:

Power-hungry 11-channel amps might need a bit of active cooling under heavy load. Specs sheet lists 1095W peak power consumption! Ideally I don't like fans in the sound room, but so long as very quiet, I can live with that.

There's literally a computer inside with all kinds of DSP capabilities, here's the current/newest firmware I'm running:

Current firmware R112-0304-1120-0131.

Beyond the usual music services like Tidal, Amazon Music, Spotify Connect, Pandora, Deezer, and protocols like Chromecast, Apple AirPlay 2 and DTS Play-Fi (possibly can stream Qobuz through this?), for us audiophiles, it's nice that this receiver is "Roon Ready" and will automatically show up as an endpoint on the network:

I can quickly play music from the Roon server within minutes with just power cable, speakers, and ethernet connected. The receiver can handle up to 192kHz PCM and DSD256. However, multichannel content is downmixed to 2.0. I hope Roon is expanding the userbase and I hope they're forward-looking when it comes to supporting devices like modern AV receivers. To allow multichannel streaming (5.1 or 7.1) to a Roon Ready device like this should be an obvious feature worth implementing widely!

For now, it looks like I'll be sticking with my fanless MiniPC streaming computer with multichannel HDMI output as Roon endpoint.

What the TV output looks like when playing Roon to Integra.
Sadly no multichannel Roon streaming at this time. 🤨

AV receivers have been incorporating digital room correction for years. This Integra has both Onkyo/Integra's AccuEQ Room Calibration as well as Dirac Live Full Bandwidth. Of the two, Dirac Live would be the significantly more powerful, preferred option. For an extra $299, you can purchase the license for Dirac Bass Control which is intended to improve bass response within the room, optimize time-domain performance, and manage multiple subwoofers - "co-optimises subwoofers and speakers" according to Dirac. Based on Internet chatter, Dirac Live Active Room Treatment (ART) may be coming to this device in 2025.

For those not familiar with the Dirac Live room correction technology, have a look at this walk-through from Mitch Barnett for Dirac Live 2 in 2020 and this review of Dirac Live 3 by Kal Rubinson in 2021. Here's an excellent Dirac Live Guide.  Maybe I'll run some tests with this machine down the road...

Needless to say, from all the logos we see on the front of the box, this multichannel receiver accepts and can decode all kinds of audio data from Dolby Atmos, to DTS, to Auro-3D with various certifications and techniques added like THX Adaptive Decorrelation, Re-EQ, Timbre Matching, or IMAX Enhanced listening modes. All of this stuff of course deviates from basic measurements like THD+N/SINAD, dynamic range, flat frequency response, etc. It's much more difficult to meaningfully measure modern receivers because of all these features that act not on "raw fidelity" to the source data, but leverages room characteristics and psychoacoustic preferences which cannot be simply quantified. Given that we will almost always listen with some kind of DSP in play (almost always at minimum some kind of bass management); there comes a point where basic measurements like low noise, low distortions, flat frequency response are no longer that important beyond a certain "good enough".

I would also be remiss to not spend a little bit of time on the thorough complement of video technologies supported for movie playback through HDMI 2.1 up to 40Gbps speed. Here's the summary table:

We see some game mode features in the mix including VRR (Variable Refresh Rate) and low-latency Quick Frame Transport (QFT). Display Stream Compression (DSC) refers to the lossy ("visually lossless") video compression. We've got ARC/eARC. And the HDR standards like HDR10, HDR10+, HLG, and accepts Dolby Vision metadata - ultimately it's up to the TV screen if it's capable of showing the high dynamic range image. (While I don't talk about video too much, we did dip into features and acronyms back in 2016 on the blog.)

As discussed a number of years back on visual angular resolution, and 4K image comparisons, I think 4K is more than good enough for the vast majority of circumstances. It's sort of like CD-resolution is generally more than good enough but hi-res 24/96 can objectively provide more details even if audibility is at best marginal. So it is with 8K where unless we have very large screens (or you pixel-peep inches away), it's more than likely overkill. Good to see that modern devices support the 100/120Hz 4K refresh modes for those gamers who want the buttery-smooth framerates with high power GPU's like the RTX 4090. 

The receiver's Bluetooth 4.2 codec supports SBC and AAC reception. The receiver can transmit SBC, aptX and aptX HD. It would have been nice to have support for AAC transmission especially with Apple wireless headphones and maybe LDAC for higher quality as well (see this for objective comparisons). In practice, I doubt I'll be using the Bluetooth feature on a device like this given the ubiquity of Bluetooth on mobile devices, so it's mainly a convenience thing rather than high fidelity playback. Also, there is a front 1/4" headphone jack for those who might want to use it, again, more of a convenience/utility thing rated at only 75mW into 32Ω with 10% THD.

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A few Internal DAC & Pre-Out Measurements...

Since it's always nice to have some objective reference for performance, let's have a peek at the XLR front right and left pre-outs in "Direct" mode which turns off DSP manipulations. Here are some THD(+N) vs. Level sweeps for a 1kHz signal using TosLink input (24/96), pre-amp volume set at "Reference" which correlates to 4Vrms output at 0dBFS (depending on whether you set the volume control to reflect absolute or relative range, reference is either 82.0 or 0 on the display; I personally prefer the "Relative" setting):

The internal DACs are dual ESS ES9026PRO (8-channel devices each). As you can see, the best performance is around -100dB THD+N at 2Vrms which I suspect is a reflection of the XLR output being derived from an internal unbalanced signal (not true differential balanced, neither are more expensive AV processors like the Marantz AV 10). Better than -90dB THD+N (less than 0.003% distortion) is already beyond the needs for human ears and not worth worrying about (ie. rational audiophiles don't get obsessed whether their DAC achieves 90 or 100 SINAD 😉).

While I'm only measuring up to 4Vrms in the graphs above, rest assured that the pre-amp can go much higher to 11Vrms XLR and 5.5Vrms RCA out to drive low-gain amps.

The internal DAC+pre-amp linearity is excellent:

Less than 0.5dB deviation to well below -100dBFS.

In the frequency domain, here's the sweep using TosLink input at 24/96, at -6dBFS level:

Very flat from 10Hz infrasonic to >40kHz ultrasonic. <0.1dB interchannel difference.

Harmonic distortion is basically all relatively innocuous 2nd and 3rd products. Notice the 3rd harmonic creeps up at higher frequencies.

Suppose we use a higher resolution DAC like the Sabaj A20d 2022 with its ES9038PRO and feed that into the XLR-in. Is the receiver's pre-amp able to deliver that higher resolution signal to the XLR pre-outs in "Direct" mode beyond the fidelity of the internal ES9026PRO DAC as shown above?

Yup, it's better than the internal DAC fed with TosLink data. Looks like the receiver is able to pass along a quieter signal through to the XLR pre-out by about -6dB. Here's a look at the 1kHz 0dBFS (4Vrms out) FFT from the Sabaj A20d 2022 passed through "Direct":

We know the Sabaj A20d is capable of -120dB THD+N from previous measurements directly from its XLR out. This shows that the receiver with its pre-amp in the chain will raise the THD+N to around -105 to -106dB THD+N which is still an improvement over the internal DAC via TosLink. As one would expect, putting any pre-amp in front of a very hi-res DAC would worsen the THD+N/SINAD. Notice a small amount of 60Hz hum down at -130dB. Most of the harmonic distortion is the 3rd. Excellent right-left channel level balance of only 0.02dB difference here.

Here's the same test with the RCA pre-out (2Vrms), notice that the left cable is only 1', the right 12' done on purpose:

The THD+N is similar to the XLR above but notice a few more noise spikes with RCA and the sensitivity to the length of the cable with the longer RCA picking up more 60Hz hum. So, while resolution is similar between XLR and RCA pre-out, if you're running longer cabling, the XLR is more resilient to distortions.

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As usual, let's be wise about how much resolution we actually "need" as human listeners in the context of blind test results like these recently and the harmonic distortion blind test a few years back.

From what I've seen, digital processing in the Integra is done at 48kHz when bass management, Dolby Upmixer, DTS:X/Neural X, Auro-3D, and Dirac are engaged. While I'd love to see 96kHz as base fs for all DSP across the board, sticking to 48kHz is understandable especially since all Dolby Atmos encoded material is currently limited to 48kHz sample rate and we've got so many channels internally (lots of DSP being done already). While audibility of high sample rates remains one of those Hi-Res Audio subjective mysteries, there is no question that multichannel audio, surround upmixing, bass management, room correction DSP are all very audible and very beneficial when employed appropriately. [Having that "Post-Hi-Res-Audio" mindset discussed previously I think is important these days.]

Subjectively, after listening for 3 nights just as a 2-channel amp "Direct" streaming using Roon to my Paradigm Signature S8v.3 floor-standers, I think it sounds great. There's a nice subjective "body" to the notes, natural tonality, wide soundstage with great "surround" effect in some of the modern pop songs, no problem with tight phantom center image and spatial depth. 150Wpc into 8Ω is more than enough power for my needs and the background noise level is very quiet without any hum or buzzing from the speakers. Bass already quite deep.

Last night, I got the surround speakers and subs all hooked up, and Dirac Live calibrated:

The measurement procedure and implementation of Dirac Live on the Android app went without a hitch. I'll fire up the Windows version of Dirac Live later to fine-tune. The sound improved substantially when playing these immersive mixes over the quality of my previous Yamaha RX-V781 set-up. Until I cut holes in my sound room ceiling, I've been using rear x.x.2 height channels, it's nice that this receiver allows me to set it as such without extra fiddling as I had done previously. Very nice integration, I've got many multichannel/Atmos albums I need to listen to again. 😁

At this point, the main thing I would love to see is multichannel Roon Ready streaming ability (7.1, up to 24/96 would be great and at <19Mbps, well within 100Mbps ethernet bandwidth). Maybe a firmware update, Integra/Roon, would be awesome? IMO, these days, all Roon Ready multichannel receivers should support multichannel streaming otherwise it really seems like a half-hearted effort especially for higher model "flagship" devices.

[Folks who care should send off a message to Integra here as I have already done - maybe "Integra's software team in Osaka, Japan" might want to take a look. While also getting Dirac Live ART running for next year? 🤔]

With that, it's time to listen! Tons of things to try out here that's much more important than simply measurements of raw "fidelity"; time to have fun with the music and movies. Maybe measurements of the Class AB amplifier output down the road if I feel like it. 😉

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To end, I just wanted to mention that for David Bowie fans, the new Blu-Ray release of The Rise and Fall of Ziggy Stardust and the Spiders from Mars (1972, DR12 multichannel) with Dolby Atmos mix is revelatory! The vocal clarity, spacing of the instruments around the listener, and timbre of each part sounded much improved compared to previous multichannel efforts and when compared to the original 2-channel stereo. Multiple "hearing things I haven't heard before" inner dialogues arose while listening to this album.

Here's a nice interview with Ken Scott the original album producer with Bowie and Atmos mix engineer Emre Ramazanoglu:

Notice the comment about the new 2.0 mixes being the Atmos fold-down with minimal adjustments - he mentioned changing vocal level minimally +/- 0.5dB. Seems like a very efficient workflow assuming consistently good results within the Atmos editing environment!

Amazing that we're in November already with the year-end Holiday Season coming soon!

Important political week coming up as we live in "interesting times". I have some popcorn ready for Tuesday night. Hope you're enjoying the music (and video!), dear audiophiles...