Passive Preamp Problem

If you can solder a bit, you could learn roughly what a passive would be like by making a simple attenuation network with a signal resistor Rs and a resistor to ground Rg such that Rs + Rg = 10K ohms. I've used a 10K ohm passive with 8' interconnects with an Aragon 4004 II and a Pass Aleph 3, and both have input impedances around 23K ohms. Not ideal according to theory--50K ohms or 100K ohms would be--but it worked fine. I suggest 4K ohms for Rs and 6K ohms for Rg, then swap them if it's too loud. For details on the network get in touch: nicetom@sonic.net. I'd also STRONGLY advise making your own passive, since it's so easy to make on that rivals or betters any commercial product. But it does take some DIY skills, mostly in the area of cabinet-making (the chassis).

The problem you have with a passive control is the cd player (Cal Audio Sigma). It has a very high output impedence of 2K (not 2) or 2000 ohms. Because it is a tubed unit, the output impedence is very high and presents a difficult load to the passive. You need to have at least a 10X difference between the two. So a cd player with output imp of 50ohms would match well with a passive showing a 500ohm input imp. I know from experience you will have restricted dynamics, harsh transients, and freq loss unless you change your source with any passive control. Your amp's input imp and sens. look good to go though. Good luck.

OK, i am staying FAR away from passive preamps, thanks Gordon!

I use a passive for the last 6 yrs. Its the "ProPassion" from Audio Synthesis - the finest I have come across.You can consider this, though a little pricey! But, sonics are a revelation. Look at www.audiosynthesis.co.uk