Tube pre-amp pop

It does sound as if you have a capacitor leaking dc. Leonard at ARC would be the person to contact. I don't see anyway to fix it w/o sending back to ARC.
It shouldn't damage your other equipment, if the pop is at a low level as you say. If it is a leaking cap, the pop can get louder though, at which point it is possible that it could harm your speakers or amplifier. Get it fixed now.
If it's brand new, just have your dealer replace it, or send it to ARC, it should be covered under warranty.

The Bryston and Rotel are solid state, correct? From my experiences, tube equipment sounds much better, but is more prone to issues like this than solid state equipment.
This is not normal ARC operation though.

Well ARC's customer service is normally very good, that should not be an issue. Has your dealer let you try any of his SP16's with your Bryston? Just to make sure that the problem is not with the Bryston? I doubt that it is, I'm just curious. Have you tried your SP-16 with another amp instead of the Bryston? Did you take your SP-16 into your dealer's shop to try with other amps? The problem is probably the SP-16, but you want to make sure that it is not the Bryston.

I think your dealer should just replace it with another SP-16. It's not like you've been running the SP-16 for 6 months and this just started happening. The problem started as soon as you started using it. I would push your dealer for replacement, not factory service. If he refuses, then I would support another dealer in the future.

Of course that's assuming that the problem does indeed lie within your SP-16.

John

Heck, if you bought both the amp and the preamp new from a local dealer, he should come to your house and figure out what the problem is for you. Especially if the dealer dropped the amp box while carrying it out. These dealers are supposed to provide some service for the premium prices you pay. Feel it safe to assume that your dealer made at least $1K on the sale of both units, he should make sure they work correctly in your home upon setup.

Don't be intimidated by the dealer. You did pay a premium, you should have new equipment that functions perfectly out of the box, or the dealer should be jumping through hoops to figure out why not. Too many bricks and mortar stores are going out of business. I fully recommend supporting them if they support you. It has to be a two way street though.

John