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.

Wonderful_electric,

That is also a good suggestion - certainly it woudl be easy to borrow another amp and test again at these low levels even a 20 watt amp would be more than enough. In "theory" Class A is better at very low volume levels. That is how my ATC amps in the amp pack run - Class A to 2/3 power. In practice, most Class AB can do very well - some would say indistinguishable given good quality. I am not sure if Class D has established a reputation one way or the other but in "theory" it should be good too (provided the ultra-high frequencies are all filtered out and nothing gets into the audible band - kind of the same issue as with a DAC). Class D, in "theory", should be capable of producing exceptional linearity - just like digital. Since I have no hands on experience of Class D I really can't comment - but several people on Audiogon have spoken positively about this type amp (based on B&O design I believe)

hi wonderful
atc have 1 year old
I´ll try soon a classe A to compare.

and guys what jumper are you using with your atc??

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.

Powerstudio,

If you take a look at this thread then you will see what I meant about volume control. Simply read what Elias Gwinn has to say about a potentiometer volume control in the first post at the top - it is best used in its "upper 80%" and should not be used in its lower "20%". That would be my rule of thumb too.

My preamp has a resistor ladder. My DAC has a pot! The resistor ladder on the preamp (Crystal 3310) is in "theory" better - so I simply run the DAC at full output (volume up all the way) and use the preamp to attenuate (besides I am lazy and really like to be able to use a remote!!!).

I suspect that many unhappy experiences with some gear may be partly related to this issue (and not the fault of the gear itself).

FWIW: I could not determine how the Avocet controls volume. If it uses a resitor ladder like the Crystal 3310 (used by Bel Cantyo, Jeff Rowland and many others) then it could be equally as good at 9 oclock as it is at 2 PM.

Of course, most people don't have the benefit of an engineering degree and are unaware that volume control can be a bit of mine field. 140 db of dynamic range of volume control sounds small ...but it is a multiplier/divider with numbers with TEN+ of zeros after them (if you are an engineer then you start to feel sorry for the poor electronics which are expected to have such linearity in two channels)!