Did you use good quality attenuators, such as the Rothwell's?
Did you use them at the end of the interconnect cables (i.e., at input jacks and not at output jacks)? The Rothwell's are designed to be used in that manner, and even apart from their internal design I would expect that their sonic effects would be quite different depending on which end of the cable they are positioned at. If the attenuator is located at the beginning of the run, the cable parameters would interact with the output impedance of the attenuator, which is likely to be considerably higher than the output impedance of the component.
Also, did you try the attenuators between power amp and preamp, as well as between cdp and preamp?
I used "Goldenjacks", which as supposedly more transparent than any other in-line attenuator. I tested them on the input of the preamp and also on the input of the power amp - the 10dB pair almost had no effect on the sound, but the 16dB basically destroyed the sound altogether. Other people have reported great things about the Goldenjacks, but this seems to be with solid state amps.
I wouldn't mind trying the Rothwells, but getting another set would be yet another hit to the wallet when i think what is ultimately needed is a cd player with an output that is not so hot, or a preamp without 30dB of gain.
Could it have something to do with the quality of resistors in the inline attenuators?
I would suspect that the Goldenjacks and the Rothwells (and any other similar attenuators) all differ somewhat in terms of the resistor values that the designers chose, and possibly also in their internal circuit configurations. Those differences, and how they match up with the component impedances, would likely overshadow any differences in resistor quality.
And neither manufacturer seems to have internal design details presented on their website, which makes it all hard to predict.
If the 10db attenuators seemed to have minimal sonic impact, though, and if 10db attenuation was insufficient, why not try having 10db attenuation at the preamp input and another 10db at the power amp input?
Thanks Al - not sure if I'll fork out more $$ to do that test! Might just get a passive volume control and leave it set at a certain level, at least this may save the experimentation with different in-line attenuators.
Any idea as to what manufacturers have a good reputation for not altering sound too much?
The "Peripheral" is intended for car audio and sells for only $16, and appears to have nickel-plated connectors. Enough said!
The Alva is intended for use with pro equipment, and therefore may not have its resistor and potentiometer values chosen to be optimal with consumer equipment. Also the amount of hardware that it includes (lots of connectors, and several switches in addition to the volume control), in combination with its $100 price, would seem to suggest that quality may not be the greatest.
I would still suggest buying a pair of Rothwell's, and using them in conjunction with the Goldenjack's so that 10db is at the input to the preamp and 10db is at the input to the power amp. That avoids the necessity of additional interconnect cables that the other devices would require (which would very conceivably have significant sonic effects due to their interaction with the output impedances of the passive volume controls). And if the Rothwell's + Goldenjacks proves to be an unsatisfactory approach I would expect you to have no trouble selling them, considering how many other people seem to have similar problems these days.
The Lightspeed Attenuator is a great passive preamp, but before buying you need to ensure it will match up with your other components, especially the amp. Typically your amps input sensitivity should be around 1V. The input impedance should be around 75kohms or higher. The output impedance of your source should also be low, with enough voltage output, 2V plus. I have plenty of play in the attenuator on my Lightspeed. Typically it sits around 12 o'clock.
With passive controls you want the control to be as high as possible to prevent coloration from the control and cables.
Most CD players do indeed have too much output (as in- way more than is needed to clip any amplifier), and frankly, most fixed attenuators do a terrible job reducing that output. However 30 db is far too much gain in a line stage- to the point that one might ask what the preamp manufacturer was thinking!
As a first step I would contact the preamp manufacturer and see if the gain can be reduced. I would do the same with the CD player manufacturer- they will not come to their senses unless somebody says something!
As opposed to passives as I am, in this case a good quality TVC would seem to me to be one of the better solutions- you have some attenuation ability and less coloration than most PVCs. OTOH, you might look into an active preamp that has a more reasonable amount of gain- 15 db is far more typical.