Inexpensive USB2.0 Digital-to-Digital Converters (DDC) Pt.1: Douk Audio U2 PRO (Upgrade Version) and SMSL PO100 PRO - initial look, about I²S-HDMI. In praise of unofficial Atmos mixes!

This SMSL unit also does MQA decoding for those who want the feature. Unlike the Douk, this box only has an LED to indicate MQA decoding status but does not tell us the PCM or DSD samplerate.

While I've tested some inexpensive devices (like the Topping D10s DAC) which have the ability to convert USB 2.0 input into S/PDIF output, I have not specifically looked into these Digital-to-Digital Converter boxes which some audiophile reviewers (like this fellow, and this) seem to rave about.

For me, there just hasn't been any reason to be particularly interested since other than conversion from one interface type to another, the other promise of such devices - the reclocking capability - just hasn't been of great interest to me. As far as I can tell from listening, it's not like jitter has ever really been much of an issue unless severely bad for any decent modern device I've ever come across even at low price points (nor was jitter really an issue even with old CD players)!

However, since I have not tested I²S/I2S/IIS, I figure I'd buy both the Douk Audio U2 PRO 2025 upgrade version (US$63; Amazon Canada) and SMSL PO100 PRO (US$74; Amazon Canada) boxes to try out; have a listen and run some measurements. Unfortunately due to time limits, I'm not quite ready to show the measurements yet, so keep an eye out for those results, perhaps next week! For now let's just introduce you to these devices and talk about the I²S-HDMI connection.

As typical of the majority of my reviews/critiques, I bought these through retail channels.

Images from San Francisco: Audio Vision SF, B&O Flagship Store, Amoeba Music. Question of greater importance: music or gear?

It's an interesting experience I think to pop into local "brick and mortar" audiophile stores when traveling (like this, this, this over the years). This past week, I've been in San Francisco visiting family. We happened to stay within walking distance from what I think is the most well-stocked audiophile gear store in the city - Audio Vision San Francisco - located in the Nob Hill neighborhood. They're opened on weekends, closed on Tuesday, and by appointment on Mondays.

Chatting with the salesperson, I was told the store opened about 26 years ago. I suspect most audiophiles will be impressed when you walk into the store and see their selection of gear sitting in the hallway!

More Audio Potpourri: What's the best sample rate converter? The other father of MP3 (James D. Johnston "JJ"). Are measurements important? And TAS' "objective" confusion.

For this post, let's discuss a few other audiophile items that have come my way in recent weeks.

First, let's talk about something I haven't brought up for awhile now: sample rate conversion (SRC).

A few weeks ago, Spoon (a.k.a. Steven Elkins of Illustrate) sent me an E-mail about his new src.hydrogenaudio.org page evaluating and ranking the qualities of various software sample rate converters. I believe the page has been online since late 2025. Check out the forum discussion about the project as well.

Audiophile Potpourri: December 2025 web traffic among audio sites, price of cables poll, and flashback 2014 while looking ahead.

Let's have some fun this week on miscellaneous topics.

Occasionally, I'll highlight items I've either written or found on audio discussion forums I think would be good to share. One reason I decided to start doing a blog beyond just contributing to forum discussions was precisely because while the public forums are great for interactions with community members, meaningful posts often become obscured behind pages and pages of chit chat, irrelevant responses, and sometimes unpleasant arguments.

[I've unfortunately witnessed situations where very meaningful threads are closed off prematurely based on the bias of moderators. Even worse, threads with useful discussions might be erased entirely from existence which I feel is an slap in the face of well-meaning participants who put their time and efforts into thoughtful reflections. This is nothing new in the audiophile world; for example last year Stereophile scrubbed their website of all public comments accumulated over decades!

While I acknowledge the right of a website's owner to do such things, that doesn't make it any more palatable. I certainly understand the need for moderation in removing nonsensical, trollish, unethical, or crude statements that add nothing to promote thoughtful discussions.]

Speaking of forums and websites, I thought here in early 2026 it would be fun to explore website traffic numbers of some of the most common audiophile/audio sites using a common metric. One can get monthly visit numbers from Similarweb for free, a well-known website traffic tracker.

miniDSP UMIK-2 USB Microphone: analog gain & optimizing self-noise. Plus audiophile gear pictures from "No Other Choice".

Last week, I discussed the miniDSP UMIK-2 USB measurement microphone and as I mentioned then, it's not often that we see much discussion about these devices among audiophiles even though they are important in helping us chase down sonic problems and of course to calibrate the sound system. To me, that calibration process is an essential part of achieving a truly "accurate" sound system once we sort out basic room set-up; assuming high-fidelity accuracy is what you're after of course!

So, before heading off to other topics, I thought I'd explore a little more about this device.

miniDSP UMIK-2 USB measurement microphone (also ambient noise floor, measurements of my system using Dirac Live with Paradigm + SVS subs)

Well, as mentioned previously, it was a great holiday season and here's another gift from Audio-Santa 🙂 - the miniDSP UMIK-2 measurement microphone. I bought this through Solen.ca here in Canada and they did a great job with the order and quick shipment. Amazon Canada often has limited stock of miniDSP products.

I'm sure the miniDSP company is well known to many audiophiles at this point. I bet many of you, like myself, already have one of their UMIK-1 microphones which I've used in a number of the acoustic measurements on this blog since 2019.

As you can imagine, the UMIK-2, initially released in late 2020, is an evolution of the UMIK-1 with upgrades which we'll talk about. First, let's have a peek at the physical device itself.

More Bass: The SVS SB-2000 Pro subwoofer (sealed, 12", 550W, DSP, Bluetooth)

Over the holidays, Santa brought me a new SVS SB-2000 Pro subwoofer (currently US$900 black ash, US$1000 piano black, Canada: black ash, piano black) for the system in the sound room. As you can see, I got the slightly more expensive shiny piano black version. As usual, I bought this from typical consumer channels.

On this blog, we've talked about full-range sound, including the importance of subwoofer(s) in order to experience "fully" all there is in our recordings. As a pop, rock, electronica, orchestral, movie-lover, the ability to experience down to 20Hz (even a little lower into "infrasound") with adequate power, and low distortion is all part of what it means to achieve "high-fidelity" audio that is transparent to the source recording. As usual, it doesn't mean I can't enjoy my music without these sub-bass frequencies! It's just nice to know that I'm not neglecting content present in those lower registers as provided by artists and audio engineers.

During the pandemic, in the spring of 2020, I bought myself an inexpensive 8" Polk PSW111 to use as an "accessory" subwoofer to help fill-in the bass response in concert with the mighty Paradigm SUB1 (1700Wrms, 6 x 8" drivers), my main subwoofer that achieves frequency response down below 20Hz. For these last 5+ years, the little Polk has done its job reasonably well but it clearly has limits. For example, when pushed up in level, I can hear the "chuffing" from the small ~4" diameter down-facing port. Also, a ported 8" sub like this can really only be expected to reproduce down to the mid-30Hz at best.

And so, moving ahead, let's spend some money to retire that little Polk sub to my main floor living room, making space for this SVS! 😁