What is needed to build a tube amp and what non?


What it should it not contain the tube amp? IMO, NFB that press the scene of the sound sending the part of signal back into the previouse stage. Unique amp must be built lineary without NFB, /in some causes linearity doesnt mean best sound/. IMO, never use tone control that change the sound. If You need more bass, use big bass speaker, if You need more high freeq. - use sensitivity tweeters, if You need meedle fr. - use sensitivity fullrange not less 8 inch. IMO, Hi End is back proportional to the number of composite parts - use simple decisions with not cheep parts- cheep parts - cheep sound!. Every passive part change the sound. IMO, in SE iron for OT must be 10-20 time more than output power, /for 5 W never use 5 W OT, but 50-100W/. IMO, in power supply use kenotrones, that provide soft start and soft amazing sound. Every time use iron chock and hmmm will be far from Your ears. IMO, do not use iron enclosure that collect noises....But your opinions?
azazello
But OTL has phase invertor like PP and signal goes between sholders and sound is close to PP.But I like my SE 2A3 RCA and my OTL 6AS7GE....
Not all OTLs are built with a phase inverter. Ours aren't- the output of the voltage amplifier goes directly to the driver tube, without an intervening phase splitter. The driver tube is then direct-coupled to the power tubes, which are in turn direct coupled to the loudspeaker. A fuse for the B+ of the power tubes has been shown to provide plenty of speaker protection over the decades...
Some ideas for best sound....

- a film cap power supply - Clarity TC
- no fuses - use high quality circuit breaker on/off
- separate trannys for B+ and filament supply
- good voltage regulation
- dual mono construction if cost allows 
--grannyring.....Im agree. About good reg. - I mean tube rec and CLCLC filter, without any kind of SS reg. that decrease dynamic of sound and complicates schem with grape of passive elements. I tried, iron chock 5-10 Hn 2 pcs is the best, IMO.