Ed,
You've had a few different power amps connected to the WiiM as I recall (B100s, Fosi ZA3s with Burson V7 Vivids op amps, V3 Monos with Sparkos op amps, probably others).
How would you compare the sound of the IOM Ultra to your previous power amps? Was considering some of the ones you've already had but the IOM Ultra looks intriguing as it would match and be a single box, though it would deny me the fun of playing with op amps and owning mono blocks.
Being this is ASR, I can tell you they all sound transparent enough that it would be hard to consistently pick them apart blind A/B.
The build quality of the IOM is absolutely tops. No question about it. It’s built like a tank! All the components are just top quality (for example the binding posts, in amazingly thick and hefty enclosure, etc.). Power was way more than sufficient for LS50 Metas. And of course aesthetically it wins by a country mile. Plus, there’s no extra power brick to deal with, and for many, that is a huge positive. Finally, it is amazingly efficient and runs no more than lukewarm. On the negatives, I can say the IOM may or may not have a limitation down the line if you ever move away from the WiiM Ultra to another streamer or source that doesn’t have a 12V trigger out, because the IOM Ultra won’t work without a 12V trigger signal, period. The power switch next to the IEC power port doesn’t force the amp on, it simply allows the amp to be triggered on by the 12V trigger. Also, the IOM sends a mild pop to the speakers when powering on or off. It’s not loud enough to do damage to the speakers, but if you frequently turn your WiiM Ultra off and on, it may be somewhat disturbing.
The V3 Monos have an audio signal-based auto-on/off that is user-defeatable, so some would consider this an advantage for overall flexibility. It doesn’t have any speaker noise when powering on or off. In terms of negatives, some would say thermal management is poor. Some components are cheap (e.g. binding posts).
ZA3 has user-defeatable 12V trigger and I think this is great. It has better thermal management than V3 Mono. The included volume dial, while not remote operable, can come in handy (for example, if running directly from an external DAC without adjustable output voltage, the built in attenuator is perfect for implementing a safety margin for incoming voltage to the amp without requiring a separate preamp). Components, like the V3 Mono, can be cheap (again, binding posts).
B100 sounds sublime, they really do—as long as you have sensitive/efficient speakers. Quality of build and components is excellent, user-defeatable 12V triggers are great. There’s still extra power bricks to deal with. Mainly the problem is low power/headroom.
-Ed
