Left channel fading in and out

Actusreus, everything Al said -- try. Got a funny feeling though you've got a weak or failing tube. Nevertheless, follow Al advice. Please let us know how your detective work fares.

Good luck.

Thank you all for good advice.

Can anything be eliminated as a potential culprit? I was going to ask whether tubes could be crossed off the list, but just saw Bifwynne's post...I was also going to suggest the speaker since I'd think any damage would be fairly obvious, not as subtle.

I will recheck the cartridge alignment. I actually checked the VTF that very same night before I started hearing the problem, and it was as intended. I probably have about 1000 hrs on my Delos.

Actsreus, I still think whatever Al says is good advice. But try this short cut. Switch speaker cables left/right. See if the fading problems moves. If not, in some goofy way I do not understand, it could be the speakers. If yes, moving downstream, check the bias of the power tubes on your amp. Btw, how many hours on the tubes? If your pushing to the outer edge of the envelope on tube life span, I'd be looking to retube regardless. After these quick checks, back to what the folks above said.

Any problems I've had with my gear -- which have been few -- were tube related.

Bifwynne,
The speaker cables are the Anti-Cables (solid core copper with a thin layer of coating) with bare ends so switching L and R would most likely not show anything.

I checked the tubes and the bias was spot on. They are relatively knew as I replaced them in late July. I'm of course talking about the power tubes in the monoblocks. I don't know how to check the input tubes in the power amps and the tubes in the line stage. Those are over year and a half old.

I might contact Rogue Audio to get Mark's input on the tubes. In the meantime, I'll follow Al's advice, which is always a good idea :) Thanks again for the suggestions; I'm pretty bummed about this.

It appears it is the speaker, after all. When I turned the system on, with the volume knob all the way down, I heard some crackling sound coming from the left tweeter. When I turned it up, with no music on, the crackling disappeared, but the fade-in and -out continued with the music playing.

The night the problem started, I apparently put a record's sleeve on the volume remote by accident and left the room to get a drink from the kitchen. With a delay, the volume began to go up. I ran back to the room, and a friend of mine who was in the room, grabbed the remote and turned the volume down, but the knob must've have gone up almost all the way up for a second or two. It is possible that it caused some damage to the tweeter. I'm surprised since we listened to several records with no issues after the remote incident before the problem revealed itself. But at this point, it's seems to be pointing to the speaker. The SR-17.5 from Silverline Audio are incredibly well-made and I know they can handle a lot (apparently max output is 126 dB), but I guess all it takes is a moment of inattention and bad luck sometimes.