Taking over a job with a 6 channel Episode amp powering restaurant low impedance speakers. The gain knobs and other setting switches were causing intermittence/crackling which I fixed with contact spray. I know it will come back again so I'm wondering what brand out there has some kind of gain adjustment knob that won't get dirty after years of service...Crown maybe? What would you recommend? Something with a web interface to adjust gain electronically?

Depending on the control, rapidly rotating the control a few dozen times usually breaks through the oxide. This can be done by the staff every few months. Of course this must be done while powered down — or else!

Sonos has announced an 8-Channel amplifier. If the restaurant signs up for the Professional App, the unit can be operated locally with a phone/pad or managed remotely.

The only thing is I wouldn't want them adjusting gain as it will mess up the balance between multiple speakers. I thought about Sonos for a second but TV sound is incorporated into the system and I'm afraid it will add a bit of a delay to the sound. I think I may suggest Blaze DSP amplifiers as they won't have any mechanical adjustments. Not sure how they'll feel about price.

Six channels, or six zones?

Caig has a contact preservative and a friend posted on FaceBook about a WD40 product that's made for contacts and controls- that may work, too.

Since you're taking over, why not tell them that it's possible that the controls will need cleaning again and set up a periodic service visit. Probably less money than replacing anything and the system will operate in the way they have become accustomed.

Without knowing the sources used and how it's all controlled, it's difficult to make recommendations but a if the cause of this is from something in the air at that location, maybe a small road case with good ventilation and a filter could work.

I had to use a road case for a 12 channel/six zone power amp because the husband splashed water into the first when he was cleaning some aquariums and the second time was because of a water leak above.