I have C2600 - the DAC is probably similar to the 2500 and it’s pretty good. A dedicated DAC will only get you 5% to 10% more depending on how picky you are. I prefer to use a PS Directstream which is more mellow but still resolving or a Benchmark DAC3 which is as dynamic and punchy as it gets. The McIntosh is in between but not quite as natural sounding as the DSD or Benchmark. With DSD and Benchmark DAC3 I feel digital has almost completely lost the “digital” sound - glare is gone. Whereas the C2600 McIntosh DAC has maybe a whisper of glare.
Of course the tube stages in the McIntosh are glorious and it makes for a very slight more analog sound on everything. Very tasteful in my opinion and akin to the way Fender guitar amps sound so clean but still have a little warmth. Some tube amps are like Vox (no negative feedback and crunchy when driven) and some are like Marshall (really crunchy much of the time) - I find the C2600 is nicely balanced with just a smidgeon of tube coloration such that you can still enjoy all genres.
I find tube distortion makes rock and pop more listenable - the added overtones help you hear or extract more instrumental details. I like the tube effect - it seems to bring out hi-hat exceptionally well. Interesting fact - our ears brain will work out and hear or create the fundamental in our heads even if it isn’t there - purely from hearing overtones...so in a busy rock mix with heavy guitars and crowded mid range - tubes can be magic. It is exactly what rock bands discovered with VOX AC15 and then the 30 - the tube distortion allowed the guitars to be heard above all the screaming girls.
