Do I have tired tubes?

During the summer when I went on vacation I unplugged my Sonic Frontiers Line 1 pre, my Musical Fidelity A3 CD, and Anthem MCA 20 amp. The pre I bought used and was around 2 years old when I bought it just over a year ago. It has the stock 6922 tubes in it. When I got back home and plugged everything back in by bass was a bit muddied and the midbass was a few dB louder than normal. The resut is now boomy poorly defined bass. Does anyone think that the tubes are the culprit? Perhaps they are due for replacement?
Change the tubes! I just bought some Lamm with 6922 and a CJ Premier 14 preamp and both need new tubes and the prior owners never thought there was a problem. Input tubes like 6922 are inexpensive also.

Tube rolling allows you to get the sound you desire out of your existing components without upgrading.

How long has the system been up and running since your return from vacation?

I sometimes alternate my tube gear and the units that have been setting for months, though less than a year, sound kind of funky for a few days. I don't leave tube gear on 7/24 and power it up for each use.

Seems odd that the tubes or anything else would degrade while being in a dormant state for a few weeks.
System has been up and running since the first week in August. The Line 1 is in standby when not in use and the tubes have some plate voltage across them to keep them warm. Everything else in the system is solid state and not likely the culprit. I have Virtual Dynamics Audition cable package throughout with biwired Paradigm Studio 100v2. Nothing in the room has been moved furniture wise. I am considering having the preamp modded by parts conneXion next year or the one after as budget allows. Have a few more pressing needs at the moment like a stand and a power conditioner. Any tube recommendations for this preamp? I don't want any rolled off highs and want firm bass with excellent mids. Thanks.
Unless someone 'messed with it', I cannot see how the 'tubes' can just go bad. If anything pull your cables and clean both the cable ends and the chassis connections. Turn the system on and let it run for a few days. Also did you by chance unhook the speakers and get one or both out of phase? Anyway, just some things to look at.

A lot of good suggestions already of course. I would suggest you consider swapping out the stock tubes anyway! There have been a rash of great 6922s posted recently at great prices (I saw several noteworthy posts today alone). Tube rolling can give your system TREMENDOUS gains.

Incidentally, repowering can cause problems. That having been said, I am surprised if the change in sound is symmetrical, though, given your description. The only time I've seen that resulted from bad power (work system - sub-fuse blow but took out four telefunkens and led to an immediate PS Audio purchase for my work system). Have you double-checked phase and connections? Any change in sound at different times of day (i.e. power issues)?

Have fun,
Alex, I pulled and reseated cable ends - didn't have any cleaner or Pro-Gold although that is coming. The VD cables are coated at the factory with some kind of protectant so that may not be the problem.

Jwaugh, yes the sound does seem symmetrical. One thing I haven't considered is tube creep. It could be that the tubes creeped out of their sockets a hair when they were powered off. This sort of thing is common in socketed ICs in computers - chip creep. Caused by thermal expansion/ contraction. Phase and connections are all good. I can invert phase from my remote on the Line 1, very handy on some CD's.

Power in my area is generally very good possibly the best on the continent. I don't even remember the last time I had a power outage. I am going to use a hospital grade outlet soon - that should help somewhat. I live in an apartment and the sound is always better in the late evening but that isn't a hard and fast rule. The block was built in 1960 just like me. I am considering getting one of the Monster power conditioners for the meantime - somewhere between a HTS2000 and HTS3500. Just out of curiosity does anyone know the difference between Monster's HTS and PB line of power conditioners?

Are gold pinned tubes necessarily better than non plated ones all else being equal?