Denon1, if you have experience with the Di150, you know what I mean when I talk about the Gamut amplifier "magic". This integrated amp opens the window to high end in a way that no amp I compared with did, and it is a bargain in my opinion. Even though I no longer own it, I cannot recommend highly enough that people listen to it.
I have had additional time to listen and gather my thoughts on the M250i and D3i combo. Slow and slight improvements during the run in period so far. My only concern with the run in was that they might change from how much I liked them at the start.
BTW, I am in no way associated with Gamut and/or any audio brand for that matter. It is just one of the few brands in audio that seems to have struck a winning formula for me and that really generates that emotional 'tingle' that makes me look forward to every listening session. I have the same high regard for e.g. Esoteric and some other brands, perhaps for a slightly different set of reasons.
Compared with the integrated, the mono/pre improvements are quite significant in certain areas, but you still have the Gamut amplifier sound which I would describe as transparent to the source, highly detailed, with impressive micro and macro dynamics presented in a slightly more musical and gentle way than some amps, but that can still give you a scary rock and roll ride when you want it. Compare the micro dynamic detail for e.g. of female vocals on Gamut vs a few other brands I have listened to, and you suddenly understand. This is where you suddenly connect with the artist's talent.
The M250i and D3i combo shows even more micro detail and has a slightly more aggressive edge in certain instruments, which felt real and natural to me. I noticed improved piano attack and leading edge on accoustic guitars, without losing the wonderful and rich interwoven harmnonics that makes music music, and without adding harshness or listener fatigue. In this regard, I find I can listen at even lower levels if I choose to than before, and still get the details I crave. Crank the volume and it just gets bigger, but not louder/harder/harsher, if you know what I mean.
Next I noticed an increased separation and breathing space between instruments and vocals, especially noticible in complex and dynamic music where 'everyone' joins in. Lesser amps often fall apart here. I would describe it in this way with the new Gamuts: someone came in and swept up the space between all the instruments. This happens without losing the overall integration of how they were meant to sound together. One CD player I auditioned which is highly regarded here did this too and was highly impressive at first, but then you notice it killed the music and integration of the artists, in my opinion anyway.
Answering the question on bass comparison: Expect much better control and musicality in the bass, but dont expect significantly more bass. These amps have all but eliminated some room interactions at some bass frequencies that I thought were purely my speakers 'fault'. I do hear more detail and harmonics in the bass than before.
I would not use these with a very lean or clinical source or speakers. You could end up with a combination that irritates you with excessive detail. I would try them as an alternative to tubes where tubes work well.
Regarding other Pre amps: no, I did not compare. I had much more confidence in the pre-amp prior to listening based on review that I trust, and I also feel happier to stay with the same brand in pre/power to avoid problems and you do know the manufacturer spent a lot of effort optimising the sound and performance of the partnership. You could possibly do better with another brand of Preamp -- I cant offer an opinion other than to perhaps warn not to go with a too lean or clinical sounding one.
