Ok, to have written a slightly more cohesive review from what I've heard so far. Initially I wasn't wowed in any way as nothing in particular stood out. I felt a little let down. As I continued to listen an the DAC warmed up I realised that everything is there with a presentation that I've never heard from any sound system before. Music is alive and breathes as a living thing. Sound stage doesn't fit my usual interpretation of a reproduced sound stage. There's width and depth, though it doesn't sound reproduced. Rather natural, as though I'm actually there in the studio. You can just hear deeper into the music.
Likewise the detail is unlike anything else I've ever heard. Notes have texture rather than being smoothed out as is often the case with rich and solid sounding DAC's. Micro and macro detail is there though it's hard to separate one from the other, it simply sounds live. Not reproduced, I'd go so far as to say I'm retrieving more detail than I did when I had my Gieseler Groß + Kraftwerk power supply. This is in no way a criticism of the Groß as it was about 1/3rd of the cost of the Mutec + Abbas Audio DAC2.2SE TDA1541A. I'd ordinarily say that layer upon layer of detail can be heard, with body and tonal richness however that's not really right either. You can hear depth and the layers of instrumental detail but everything is perfectly integrated. It makes other music I've heard sound like a flat 2 dimensional reproduction in comparison. Dynamics are greater than I've ever experienced before ranging from extremely quiet to quite loud, with impact and slam where it has been recorded. In a way the DAC combines the richness, body and imaging of my modified Muji Studio DAC II with the superior detail and accuracy of the Gieseler Groß, though that's not accurate either it though as it betters both of those units on their strong points as well and then some. All the best of the better units I've heard and none of the negatives. It also seems to to have pace, rythm and drive where music has it which I have personally never experienced before.... Even with vinyl.
I think Abbas' devices are all about cohesion in tone, detail sound staging etc. It's about emotional content in the music and impossible to measure quantitatively or individually, only as a whole. It's just beautiful.
I've read, and experienced that some NOS DAC's have rolled off highs and bass with less detail to boot. Nothing could be further from what I'm experiencing via the Abbas. It has deep weighty bass beyond what I've heard before, and treble extension that will match that of modern oversampling DAC's It's just that everything ties together so seamlessly that you hear everything as a whole rather than focussing on individual parts of what it's doing well as you do with other units. That said, never before has it been easier to follow any particular segment of a recording. Never have I heard music presented in such a way. It flows and displays a sense of timing which even my vinyl setup doesn't exhibit....
Another thing that surprises me is that if I didn't already know this DAC was tubed I'd never pick that it was a tube DAC. I seems in no way coloured though rather chelelion like changes from one recording to the next. It outperforms solid state components I've heard in the area's that solid state gear is generally touted to have advantages over tubes. Namely deep tight bass, speed, precision, impact and dynamics.... It's also the quietest component I've run in terms of noise at odds with other tube geat I've run. Anyway, I'm not sure how to explain this better.... I think it has to be experienced in person for someone to truly understand.
I'm just going to sit here and keep enjoying what my ears tell me. I'm simply not good enough with words to describe what I'm hearing any better. It's beyond me. The sound defies description.
The other thing is that over long listening sessions it's performance has continued to improve. I'm not sure I can really write anything further as it would need a talented wordsmith to explain this so I'll leave it at that. I mean how do you explain do I explain a totally transparent piece of gear?