The Boulder/Gryphon/MSB amps are the top three I would choose too. I haven’t had a lot of time with the Sim 888’s, so I can’t say definitively, but the Sim 860v2 is a terrific sub-$20K performer.
The MSB amps are the proverbial odd ball here, because you are talking somewhat new world class amps from a company more known for world class DAC’s. But the amps are all that - and more. The MSB amps TRULY perform above and beyond when paired with the MSB DAC’s. Why? The output impedance of the DAC is a perfect match for the 75ohm input impedance of the amp. Thankfully, MSB was one step ahead and also put a multiple input impedance selector switch on the back to ensure their amps will pair very well with more than just their DAC’s.
As a friend of mine and I found out on Friday after several hours, choosing between the Boulder and the Gryphon amps is not an easy task. Both have exceptional, unique qualities. The Gryphon really pairs well with the Gryphon preamp and takes things to a whole new level and we love the green bias link between the two. The Boulder amps seemed to pair well with it’s own preamp, but other preamps as well and never really got “hot”. But the bass from the Gryphon is seriously subterranean and quite addictive. The transparency from the Boulder was also quite addictive. Both are world class. Oddly, one only comes in silver and the other only comes in black! Maybe that’s the way to choose. ?? [emoji6]
Although I personally love a preamp in the system (old habits are hard to break?). The full blown preamp module from MSB sure helps make Jeff’s point in the article.
As for mono vs stereo, this is a little trickier. If the amp is made purposely as a mono, then yes, generally that’s the way to go. But some amps which are switchable, you have to watch the minimum ohm rating a little closer and more carefully match with your speakers. That being said, there are a few cases where Joe and I have found the stereo version to be a little sweeter sounding. Hegel H30 comes to mind.
Another great article again showing world class products from world class companies, all of which resemble the term “luxury”.