[Early B.]

Sometimes when a power surge hits my house and afterwards when I turn on my system, the sound is low and doesn't change when I increase or decrease the volume. I have to reboot it (turn the power conditioner off and turn it back on). Once I do that, everything returns to normal.

Why does this occur? Where is the issue -- power conditioner, preamp, amps, DAC, or transport? 

[richidoo]

Some microcontroller (probably in the preamp where the volume control lives) is getting hung from overvoltage. Maybe the microcontroller that operates the remote or relay stepped volume control. Or if CDP has volume control that resets to safe default level, etc. Some microcontroller is going dumb on overvoltage.

Your power conditioner is not protecting from surge? Maybe it is just a noise filter.

A whole house surge protector is a good investment. I installed this one last year:
https://www.amazon.com/gp/product/B01AQAKRSS

[Early B.]

OK, maybe you're onto something in the preamp. The volume control was upgraded to a Tent volume control before I bought it.

My transport doesn't have volume control.

My power conditioner is badass -- it's a Zenwave Audio modded SurgeX.

[JohnR]

Does this "badass" power conditioner keep the output voltage constant? If this problem happens a lot, I wonder if it might be worth looking into one that does. Autoformer units will deal with some over/undervoltage but if it's actually a short supply interruption (sounds like it might be) then a UPS type of unit might be needed.

[Early B.]

Does this "badass" power conditioner keep the output voltage constant? If this problem happens a lot, I wonder if it might be worth looking into one that does.

The problem doesn't happen a lot. Maybe once or twice per year. A few days ago, our area experienced several, rapid fire brown outs. I'm assuming that was the culprit.

Your point, though, is the power conditioner might be the source of this issue. Not sure. I have 4 other SurgeX power conditioners in my home, and none of the others exhibit this behavior.     

[JohnR]

Your point, though, is the power conditioner might be the source of this issue.

No,  I mean that the conditioner can't do anything about low voltage on the line, it's not causing the issue. To deal with that you need something else. Could also be related to the power supply design of the preamp.

[srb]

I'm thinking along the same lines as richidoo, the digitally-controlled TentLabs volume control being the prime suspect.

[richidoo]

A surge is overvoltage. A brownout is a voltage dip and SurgeX will not affect that. If it's brownouts that are causing this problem that would better explain why the Tent chip hangs instead of breaks. The SurgeX will protect from big surge, but a power regenerator is needed to cure undervoltage brownouts, and it improves sound quality dramatically too.

[Early B.]

I'm thinking along the same lines as richidoo, the digitally-controlled TentLabs volume control being the prime suspect.

Yeah, me, too. One more possible clue -- my preamp doesn't have a power switch. It's always in stand-by mode.

Next time this low volume thing occurs, instead of rebooting the whole system, I'll unplug the preamp and plug it back in to determine definitely if the preamp is the culprit.