Tube gurus, if you please.
If you'd welcome a non-tube guru's thoughts, here are mine:
1. Is it correct to assume that most of the 300Bs, 2A3s, etc. that pinoydiophiles own are DIY amps? Is going the DIY route the best way to tube amp ownership?
I don't have statistics but my impresions is most SET-using Pinoydiophiles either built their amps from the ground up (e.g., ArnoldC, Mickey, Toobs, etc.) or started with a commercially available model then modded it (Racio, AudioNote2003, etc.).
Going DIY / commercial have their pros & cons. Remember also that there are stuff that blurs the lines of both DIY & commercial amps. See Hypertriode's stuff.
4. Where would you spend your money if had one choice only, on good iron or on good tubes?
I'd go for balance. One of the most valuable lessons I learned since meeting Vintage Dog, Toobs, johnmarc0, etc. is that it's not guaranteed that if you put all the high-end, "botique" parts, you'd get great sound.
A lot of it boils down to taste also.
5. What type of tube amps come in pairs and what come in a single chassis? What factor dictates this?
Pairs? The more common execution of "pairs" is monoblock amps, i.e., each channel comes in its own chassis.
The advantage of this approach is you have separate power supplies for each channel (though you can also have "dual-mono" construction in 1 chassis). You can also get the amps closer to your speakers thus calling for shorter speaker cable runs. If you're using Kondo-san's KSL-SPz, that means very significant savings.
Another execution is designers separate the power supplies from the gain and output stages. I'm not sure what benefits this gives but I suspect less power supply-induced noise affects the part where signal is amplified.
6. Is it correct to assume that most gurus prefer SET amps to push-pull amps? Why?
VD onse said that at times, there are music or things in the music that he can only get when listening to push pulls.
SET has more stringent requirements than push-pulls in terms of speaker matching specially, both in terms of impedance and sensitivity across the audible frequency range.
While I am a firm believer in the magic SET's posses, my problem has been finding speakers that simultaneously are: to my ear's liking, able to fit in my small listening area, and something I can afford.
7. How come push pull amps have more power? Is the ST70 push-pull? How can one tell?
Yes, ST70 is PP.
I'd leave the "how can one tell" part to the experts.
There are high power SETs like
http://www.wavac-audio.gr.jp/he833_e.htmlBut even the more "affordable" higher power SETs like those based on the 211 are thought of as having missed the point of the less powerful 300B, 2A3, VT-52, etc.
8. You've got the high efficiency speakers and your tube amp, what other money draining thing do you need to spend on? (aside from your sources & cables)
You'd like some tube dampers like those from Hal-O.
You'd also like to keep a spare set of tubes, if not build a collection.
You'd like to mod later on...amorphous or silver tansformers (there is a raging debate on this), higher grade caps (or replacing them with more trannies), resistors, silver wiring, etc.
You'd also like to get other types of SETs...so you listen to xxx SET for aaa music using 111 speaker, yyy SET for bbb music for 222 speaker, etc.
Other things to spend on are pretty much like non-SET, non-high sens speakers, basically.
Oh, post this query on Pinoydiophiles...you may get more responses.
