I tried the SR1a with a Devialet Expert 200, which is supposed to deliver 200w into 6Ω, and that was not a successful pairing. It would work at low playback levels, but turning things up became problematic fairly quickly - especially with music that had lots of high-frequency content. The sound was rough and edgy (the SR1a are ruthlessly revealing and will expose any limits further up the chain). I was not able to get them to kick or slam or deliver the impact that they are quite definitely capable of, either.
I didn’t have a second unit around to test with, so I have no idea if that was an issue for that specific amplifier, or an issue with the design/implementation of the Expert 200.
With normal speakers, most of the time you’re only using a handful of watts (typically 5 or less) and it’s only big dynamic excursions, and/or stuff with lots of low-frequency content, that draws a lot of power. While that’s true of the SR1a too, the power ramp-up they require quickly becomes more than typical, efficient, speakers, so amplifiers will generally wind up working rather harder with the SR1a for a given track than they would with a normal-efficiency speaker.
That may trip up some class D designs (or related hybrids), as they often wind up in very sleek chassis with limited thermal dissipation capacity, and running harder, for longer periods, can result in limited power, either dynamically, or as a hard limit (which is one reason why class D studio amps/PA amps usually have heavily vented cases and fans in them, even though in most use cases they’ll run cold).
I suspect, but don’t know for sure, that that is what tripped up the Expert 200 I tried with the SR1a.
I can say that I’ve not had any issues with driving the SR1a with amplifiers that use SMPS. The Linn Akurate 4200, Chord Étude, and Benchmark AHB2 all have SMPS driving them and all produced excellent result, though none of them are class D, either.
Hopefully it works out fine and the issue I found was with that specific unit. Lower powered amplifiers really don’t do well with the SR1a. The AIC 10 that I saw much lauded for them elsewhere, which is a 10W design, didn’t light them up at all … even compared to a cheapy 2-channel 200W THX HT amp.
If it doesn’t … then a Vidar or a Jotunheim R both will work to drive them, and either can be fed from your Devialet 120.