Solid state; when would you use tubes?

I am looking for a more holistic answer, and less a solid state manifesto.

Chazzbo: I thought I was the only insomniac who wrote rambling minifestos. However even with your mind going at the speed of light which it doesn't by rules of nuerotransmision it can work at more than one thing at once and become a tad congested as if you apply too much power to a high efficiency speaker. All that being said you have outlined much of the conventional thinking about how to incorporate tubes into your system. Many of my audiogon buddies have been proponents of the sure footed, albeit no fun in finding small NOS signal tubes, SS preamp with a tube power amp. This yields the beauty of tubes without the combined distortion of using both Tube pres and Tube power. I personal use the more common complicated tube pre with 6 nine pin miniatures rolled to my heart's delight, with SS amps. You didn't mention that tube rolling can become an insane and expensive addiction by itself, I have more tubes than I will use in several lifetimes, sometimes called hoarding but really a sign of mania or obsession. That is what you call a tangent not manifesto BTW. The point I was attempting to make although I read your stream of thought rather quickly, is that the latest development is to go from a tube or non tubed source directly into a tube power amp. Only if you one source as do many I use a few. This avoids the problems of a pre altogether. The other option for those considering tubes is a moderately powered tube integrated which I own which is generally quite affordable and uses a classic topography of small input tubes, to drivers ,to power output tubes with the correct transformers along the way. I believe this has been around for decades and is called the Mullard Longtail configuration.
That last option can be very satisfying and does not limit your speakere choice to the exent SETs do. Mine drives VSA VR2s to listenable levels without excessive or audible distortion and they are 89db but hold their impedance with only a 6 inch midrange and a 6 inch woofer per, 2 tweeters but they draw almost nothing.
To answer your thread question the cliche is you use solid state-
A. If you prefer it's sound because tubes, which do not I repeat to not roll of highs tubes generally birighter sound desirable "sparkle." Your SS amp may in fact have greater roll off in the teble than tubes. OR
B.) When you cannot tolerate loose bass because most tube amps that are affordable anyway cannot deliver 100watts or more which is needed to control a bass heavy sound . So you do
C.) The classic biamp solution which has the benefits of both an amp or pair of monoblock tubes for the trble and misrange in a biwired speaker for the magical soundstage and beauty of tubes (depending on the one you choose EL34s as he said are great midrangey tubes even sweeter but less potent are EL84s ala Manley Stingrays et. al. and a potent SS amp to power the woofers/low end. There are tricks for doing this such that the volume output from both amps is equivalent. Do a search on forum topics and you'll find plenty of info, on how it can be done. If not here then search the AA site for FAQs and they have a detailed description for you.
To sum up You use tubes if you are manic and sleep poorly or when you really want musical involevement, deep and realistic sounding soundstage, and tonal timbrance that only tubes seem to deliver. But please make no mistake except with non refurbished or up non graded low power vintage- tube gear pre solid state era -i.e. pre early 60s -you will not get a"tubey" sound which people still think means dark, closed in, ill defined and rolled off sound. Use tubes when you hear them set up properly and like what you hear.
As a suggestion if you aren't using very demanding speakers try an inexpensive tube integrated just don't think it will play the crescendo of "Freebird" at 100db.

Chazzbo: I will forward what a tube buffer can really do which has more to do with its ability to act as a follower letting the impedance your source sees as virtually zero, thus giving the source all the power the source can providee and the power of the buffer, to manipulate the signal in an unencumbered state. The desesigner of REX speakers (see the latest 6 moons) is a friend and one one those Russian physics genius types who built one with a log or actually greater strength than the X-cans.He explained it to me. I too thought it meant using tubes to alter the sonics but it does so in a most indirect way they never serve as "active" tubes and don't supply any gain, they are passive, they are "buffers" only.

Biomimetic: If you are used to solid state and are curious you really do need to do yourself a gear favor and get up close and personal with an all tube based system for awhile. I was a complete solid state fanatic and for years vowed I would nenver go near that archaic technology, but now I am converted. Over the past two years I have assembled a second all tube based system around a CJ integreated, their CDP, a tube phono stage, and modest speakers and TT. I now listen to this system 90% of the time simply becuase I can listen to it at any level and I ALWAYS get pulled into the music without even trying. In fact I am listnieng to it as I write and am constantly distracted because this system, the total of which goes for about $5K, sounds so damn good. So mark me converted. Don't go partial on this, go whole hog and be happy.

FWIW, My first tube purchase was a tubed CDP (Cal Aria) in the mid 80's. BIG tonal improvement! My next tubes purchase was in a Pre-amp. Even bigger improvement. I upgraded to a Trans - DAC (Tubed combo). Similar tonal balance but with greater resolution. Several years later I purchased my first tube amp. Last year I purchased my first SS CDP since my original SONY 101 just to see what high quality CDP's can sound like w/tubes in the Pre & amp. Pretty good I'd say. Lacking a tad bit of air in the highs, but a very solid and musical sound (Wadia vs BAT).

In retrospect I think, at least for me, the pre-amp was the greatest single improvement and the amp was the second biggest improvement. I don't think one necessarily needs a tubed CDP or DAC any longer for high quality sound.

FWIW - YMMV.

As an A-Gon member, I appreciate the time put into the above posts, but good grief, please spell check, proof-read and organize what you write. Stream-of-consciousness blather is really obnoxious and no one has the patience to read it.

My experience after years in this game is that, if mixing and matching tube and SS gear is what you are in to, a top solid-state preamp paired with an equally good tube amp is generally the best approach (because of the quiet of great SS preamps, and the layering of space and timbre provided by great tube amps), but they are also cost-prohibitive. Less-than-great SS preamps sound, well, solid-state, and only $$$$ tube amps have the high-quality output transformers and power supplies required to control low-impedence speakers. If you are on a budget, a good tube preamp with a decent SS amp like a Bryston 4B-ST and careful choice of cabling, in my opinion, will get you surprisingly close.

As the studies done in the 50's proved, the small-signal tubes in preamps and DAC's are good for a hell of a lot more than 10,000 hours if left on 24/7, as they pass virtually no current -- the only thing that will kill them is infant mortality (duds will croak in the first 250 hours or so) and on/off cycles. While there are a few hot-rod preamp circuits out there that stress the tubes, you are generally best off leaving a tube preamp on 24/7 with the volume turned down and mute switch engaged when not in use, replacing the tubes every three years or so.