Cable conundrum: Parasound A21 with RCA AND XLR

Milpai,
At this point, i would have definitely said good quality RCA's are the way to go in my system if i could only run one type. The XLR's just did not have the the same sonic vibrancy/detail/depth. The initial increase in gain, actually seemed to deteriorate the sound, so i lowered the gains on the amp.

EG,

I can't formulate a precise explanation for your findings, but I suspect that if you put the ground lift switch to "normal" you may very well obtain results with only one set of cables connected that are similar to what you have obtained with both connected.

The ground lift switch isolates the ground sleeves of the rca connectors (and possibly also the ground wire on pin 1 of the xlr's) from the amp's chassis. I would only use that position if it is necessary to prevent ground loop hum or buzz. That isolation could conceivably account, in subtle ways related to the grounds, leakage paths, stray capacitances, etc. within the amp, for the sonic effects you observed when only one set of cables was connected.

Having both cable sets connected, while the ground switch is in the lift position, could conceivably alter the paths and impedances through which signal return currents flow, between the input circuits of the amp and the preamp. That in turn could conceivably alter or undo the sonic effects of having the cable grounds isolated from chassis.

That's all conjectural, but I definitely think it is worth reassessing your findings with the ground lift switch set to normal.

Re your question about phasing, I don't see any relevance, because neither the relative phase nor the absolute phase (polarity) of whatever inputs are selected (balanced or unbalanced) would be affected by the presence of the other set of cables.

Regards,
-- Al

I have a Parasound C2 preamp processor normally connected to a Parasound A23 amp using balanced cables. My ground switch was and is in the normal position and the cable switch set for balanced cables. I decided to try adding a set of unbalanced cables between the C2 and A23 based on Evergrey's post. The sound seemed fuller and more detailed through my Salk SongTower Speakers with both balanced and unbalanced cables connected whether the amp was switched to the balanced or unbalanced cable position. The unbalanced position sounded slightly better to me when the sound level was matched.
I do not believe the position of the ground switch is the explanation since mine is set to normal (not lifted). I have noted that even when the switch on the amp is in the wrong position for the type of cables used (that is unbalanced if only balanced cables are used or balanced if only unbalanced cables are used) there is some sound output albeit at a lower level. It may be that the amp is being input by both sets of cables although one at a much lower level that for reasons unknown to me gives a richer sound at the same volume. Then again this may be a placebo effect. In any case it was worth trying as I had the spare cables available. YMMV.

Well, this investigation has taken a turn for the worse. I decided to remove the Synergistic RCA's from te amp and turn the ground switch to 'normal'. After i turned my equipment back on from the cable change, i lost sound out of the left chennel. I've tried every scenario to see if it wasn't my source, preamp, speakers or different cables. I've deduced that my amp blew a channel. The 4 buss fuses inside, although taped uo to hide the filament, seemed to still work because the 2 blue lights on te front panel were lit up, the 'Hi Temp' light was off, and te right channel worked.
This is a total bummer and now i have contacted Parasound to see what my options are.
Thanks to everyone for all your input.
Mlenn, are you going to leave both IC's sets connected? didn't know that it would have a similar result for others or not.

Evergrey, sorry to hear about the problem with your amp. I do not know why this problem would be related to your cable change if the system was off when the change occurred as you indicated. Thanks for the warning and please keep us updated on what you hear from Parasound.

Yes, I plan to leave both sets of cables connected to my A23 for the present, but will continue to avoid any changes in switches or cables unless the equipment is off. I blew the external fuse on my A21 (used in separate HT system) once when thoughtlessly switching from ground to lift with the system on. Fortunately, a simple replacement of the fuse fixed my problem. Lesson learned.

My C2 will sometimes switch into a silent protection mode if I touch the unit or connected equipment and get a static spark. Switching to another source or turning mute on and off returns the unit to normal operation. I appreciate this is likely unrelated to your A21 problem.

Hope you get your amp problem resolved soon.