ATC scm 19 upgrade ??

BTW Powerestudio. How long have you had them? Maybe they have yet to fully burn in yet? Cos it takes quite a bit of run in for the bass to fill in for the ATCs. Also something you should know is that high power output amplifiers don't do so good at low volumes, mainly being the greater presence in distortion levels at low levels than mid levels. Also Iceamps actually performs best powering lower impedance loudspeakers (<4ohm) than the usual 8ohms loudspeakers. Maybe try switching to an affordable Class A amp instead since you don't really need all that digital power at your disposal.

Oh sorry powerstudio.
Can't help you there. I am using the active 20s so no jumpers involved. Thing is not the technology of the Iceamps that has the problem. It is simply the fact that Class D has not fully matured yet, it outputs high distortion in the higher frequencies and is not very stable into higher impedance loads. Read the stereophile review of the s300 and you will see. Plus I was actually warned by my dealer not to use the Bel Canto power amps to drive passive ATCs when I told him I was getting the DAC3. Not sure why but anyways I got the active so... no problems there.