->       1. How long should you expect to get out of a set of tubes?
Varies. 1-2 yrs. of daily use is typical. 15-20 yrs. of real light use is not
at all unheard of.
->       2. How long should a tube unit be allowed to "warm up"
->          before playing?
Varies. :-) Sovtek 6550's stabilize in about 5-10 minutes; sound decent in 2.
->       3. Do the "tube covers" (look like little tube sweaters)
->          actually increase tube life?
They can. Some can also cause hot spots. For output tubes, I like the Pearl
coolers or their equivilant design, for smaller driver tubes I like the
neoprene/sorbothane rings when high heat ISN'T an issue.
->       4. What things are tube amps/pre-amps sensitive to/about
->          that might cause them NOT to play at their optimum?
Bad tubes/tube matching, poor output xformer-to-speaker impeadance matching.
->       5. Are tube units more or less sensitive to vibration and
->          should extraordinary effort be put into their isolation?
More on a), no on b) although the hardcore will debate my "no on b)" opinion.
->       6. Can a tube amp like I described be placed in an enclosed
->          (no back) entertainment center without overheating etc
->          or - - must they be in the open air due to heat? (I have
->          often seen them called "space heaters").
Could be an issue. A small boxer fan -may- be necessary; depends on how much
free air space actually exists vs. air movement.
->       7. Am I nuts for even considering getting into tubes?
NOT AT ALL!
->       I would also appreciate thoughts and suggestions on the S.G.JoLida
-> integrated amp mentioned above. The smallest of the three amps got some 
good
-> ink in Stereophile recently, but that does not substitute for real people
-> experience.
The JoLida is a reasonable entry level piece; decent design/components, 
AVERAGE
fit and finish. It can be found for much less $$$ from J&R Music World in 
.Y.
via mail order or on the used market!
Hope these opinions help!
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