Chris - I had a friend who believed that DAC IC should have current output to avoid I/V converter inside and be followed by the tube and discrete transistor circuits to avoid opamp. DAC itself has current sources build using monolithic, opamp like, technology - no escape from that.
I don't have enough experience to judge and my system is very modest, but logic tells me that added distortions add dynamics to the sound (distorted guitar vs clean jazz guitar). Yes, Benchmark sounded lifeless to me at first but it doesn't anymore while it still sounds extremely transparent and clean. I got used to this sound - or learned to listen, if you prefer. I read post where somebody asks how to make sound warmer and less detailed - read "exaggerate even harmonics and add a little distortion" (I advised blanket over speakers).
My small class D amp according to some Audiogon members (with better ears and more experience) has some problems with highs and harmonic structure but I think that for the money it is a great bargain.
Stereophile rated A, couple years ago, amplifier that costs $500k. In my opinion review wasn't necessary because any amplifier with that price tag and company still in business will be rated A. Everything is a matter of money and most of the time people ask for the best bargain and synergy in their systems. Opamps, in my opinion, are very good bargain.