I've gone back to the balanced interconnects -- no initial thump. The hiss stopped when pre-amp powered off, amp powered on, so does not seem to be an amp problem.
McIntosh C50 preamp having a hissy fit! Help!
The setup is: Esoteric K-03x CD player, McIntosh C50 preamp (both plugged into a Furman Elite DMI 15 power conditioner, Synergistic Research power cable for the C50), Pass Labs X350.5 power amp (plugged into wall outlet), KEF Blades.
The problem: the Uni-Q drivers emit a low-level, but angry hiss. Not audible perhaps 18 in. away from speakers. On rare occasion a tiny "tik" could be heard while playing a CD. I traced the source to the C50 preamp -- shut off, no hiss, even though the power amp remained on. I switched out a couple pair balanced cables (had been using Acoustic Zen Wow) -- no difference. However, with unbalanced RCA interconnects the hiss was mitigated by perhaps 80% -- you have to put ears up to the speaker to hear a constant flutter and hiss. But there is also a short "boop" that comes from the right channel upon powering up the amp (after C50 has been powered up) -- also never happened before.
I had a completely silent background with this configuration (incl. balanced Wow interconnects) with ML Summit X speakers.
Any insights on what's causing / how to eliminate the noise?
Many thanks for your kind and helpful insights.
The problem: the Uni-Q drivers emit a low-level, but angry hiss. Not audible perhaps 18 in. away from speakers. On rare occasion a tiny "tik" could be heard while playing a CD. I traced the source to the C50 preamp -- shut off, no hiss, even though the power amp remained on. I switched out a couple pair balanced cables (had been using Acoustic Zen Wow) -- no difference. However, with unbalanced RCA interconnects the hiss was mitigated by perhaps 80% -- you have to put ears up to the speaker to hear a constant flutter and hiss. But there is also a short "boop" that comes from the right channel upon powering up the amp (after C50 has been powered up) -- also never happened before.
I had a completely silent background with this configuration (incl. balanced Wow interconnects) with ML Summit X speakers.
Any insights on what's causing / how to eliminate the noise?
Many thanks for your kind and helpful insights.