Tube advice

Not sure about the newer ones, but I would stick with ARC's tubes if the newer amps are anything like the older ones.  They were very hard to bias correctly and tubes often would fail on first use because of that.  Andy Bouwman told me years ago that he couldn't guarantee any tubes he sold if they were being used in ARC amps, for that reason.  Personally, I'd stick with ARC's tubes, unless the biasing is easier nowadays. 

adg101 - intersting, so it is possible for my ARC installed tubes in my vt100 mk II to fall out of proper bias over time?  

In the old, old days, the amplifiers designed by William Zane Johnson, founder of ARC, were well known to run the tubes very hard, and failures were common.  To deal with this issue, ARC was known in those days to "update" their amplifiers quite frequently.  I never knew whether they were trying to convince customers that the newest version of whatever amplifier was "fixed" or what they were really doing.  But tube failure, sometimes catastrophic, was a price you paid for great sound. In any case, Mr. Johnson has long been out of the ARC design picture, and I have not heard in many years that modern ARC amplifiers were particularly unreliable.  If you know what you are doing with bias adjustments, you could source the tubes from Tube Depot, or one step up the scale would be to buy selected tubes from Kevin Deal or Jim McShane, which might cost a bit more but those guys really do test the tubes before selling them.  Even the latter sources might be less expensive than buying tubes from ARC.  Then you can start at bias point where the plate dissipation is at first low-ish and let the tubes break in for several hours before turning up the current, if indeed the tubes are stressed in modern ARC designs. But Tube Depot is a reputable source, far more reliable than eBay might be, for example. Keep in mind that tubes age and change parameters over time, no matter who sold them to you.  So, long term, there are no guarantees regardless of source.

Yes, marktomaras, ALL tubes will require re-biasing once in a  while over time.

Thanks for all the great advice. These are the amps I have:
Phono Ref 2 SE
Ref 5 SE PreAmp
Ref 75 Power

The Ref 75 has easy access bias from the front panel so that's probably pretty safe. I'd definitely have to do some homework on how to bias the tubes on the other units.
I had a Ref 110 before the Ref 75 and the recommended tube run is 2000 hours. I pushed my luck and squeezed another 300 or so hours out of it before frying the fuse and fuse connector, about $200 repair. I guess that's the price we pay for loving tubes and for me not believing the specs.

marktomaras - yes your ARC amp will in time drop out of bias; the VT100 is not a self biasing amp... double check but I'm pretty sure it's not. I know the VT50 is not and my dad checks his often and checks his tubes as well on his tube tester's.

moryoga - your preamps are simple. Your Ref 75 is another animal but as you mentioned easy to bias over older ARC amps. I agree probably best to buy from ARC on your Ref 75. For your preamps I have had great luck buying tubes from Cryoset Certified. I'm not sure if you can bias your preamps manually as I would guess they are self biasing but not sure. You have some very nice equipment - I'd invest in a tube tester. Not sure how people with tubes survive without one unless they have a friend or shop close by.