Tubey, better late than never - I just replaced all NE5532 amps in Benchmark DAC1 with OPA1612 and play it so far for few hours. NE5532 is a very good amplifier especially for the price ($0.5). OPA1612 is fuller sounding - especially lower midrange but also more dynamic. Transients are stronger, both rimshots of snare drum and big-band trumpets. It is a little bit cleaner and perhaps because of that instruments are more defined in space. A little improved width of the image and maybe slightly depth as well. NE5532 is very flat and even sounding but is no comparison to OPA1612. Overall balance with new amp is a little darker but with better transients. OPA1612 is open sounding but is a little warmer possibly because of the lower midrange roundness. So far I don't hear any harsh sibilants (very clean) but it is virtue of my speakers. What else, maybe cleaner more resolved sound at congested parts.
I listen now to very well recorded John Pizarelli meets the Beatles having loudness adjusted to comfortable low level but trumpets come in few moments too loud. I don't remember that before but I like it.
OPA1612 is the same thing as OPA2211 (dual of OPA211) but with worse voltage offset (dedicated to audio). I don't care since my amp bandwidth starts at few Hz - most likely DC servo to take out unbalance. I'm still hesitant to short output caps since I might forget about it and use Benchmark with different power amp. OPA2211 is more expensive and does not guarantee acceptable offset because of other parts like D/A chip itself. OPA1612 has extremely low crosstalk - possibly dual die but some reported better results with two OPA1611. In my opinion it might be placebo effect.
I listen now to very well recorded John Pizarelli meets the Beatles having loudness adjusted to comfortable low level but trumpets come in few moments too loud. I don't remember that before but I like it.
OPA1612 is the same thing as OPA2211 (dual of OPA211) but with worse voltage offset (dedicated to audio). I don't care since my amp bandwidth starts at few Hz - most likely DC servo to take out unbalance. I'm still hesitant to short output caps since I might forget about it and use Benchmark with different power amp. OPA2211 is more expensive and does not guarantee acceptable offset because of other parts like D/A chip itself. OPA1612 has extremely low crosstalk - possibly dual die but some reported better results with two OPA1611. In my opinion it might be placebo effect.