I've owned the D115 Mk2 which is an all tube design. My listening experiences with the D125 which is the first of their hybrids preceeding the Classic series, is so limited it would be of no benefit to compare the two. I will say I preferred their all tube designs of the 80's to their hybrid Classic series. If you get a chance you should just hear the D79 from the 70's, one of ARC's best efforts.
The D115 mk2's notable characteristic, even by todays standards, is the large stage and a sweet midrange, a very open sound. High frequency and bass are not up to the best offered today but this would be relative to the system it will be used in. Bass is powerful but doesn't have the control of a ss amp, not many tube amps do.
A matter of note is that the amp has 8 6550 tubes that are biased quite high, 65ma. This adds up to a lot of heat. Also you may want to consider the hassle of biasing when replacing outputs, ARC didn't make it too easy on this one. Overall it is a wonderful amp. I personally have had no problems other than tube replacements and would certainly recommend it to someone getting into tubes for the first time.
The D115 mk2's notable characteristic, even by todays standards, is the large stage and a sweet midrange, a very open sound. High frequency and bass are not up to the best offered today but this would be relative to the system it will be used in. Bass is powerful but doesn't have the control of a ss amp, not many tube amps do.
A matter of note is that the amp has 8 6550 tubes that are biased quite high, 65ma. This adds up to a lot of heat. Also you may want to consider the hassle of biasing when replacing outputs, ARC didn't make it too easy on this one. Overall it is a wonderful amp. I personally have had no problems other than tube replacements and would certainly recommend it to someone getting into tubes for the first time.