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
If you have not build anything like it before start with a complete kit to get you feet wet.  

https://www.ebay.com/itm/Pair-of-VTA-M-125-125-watt-tube-monoblock-amplifier-KITS/302804291604?hash=...

When building with tubes remember your dealing with lethal voltages - be careful - especially if you have no experience.

Best of Luck

Peter
pbnaudio.....I have experience  with tubes more 20 years and I have more than 50 DIY projects - 300B, 2A3, 6L6, EL11, EL34, EL84, 5005,  GK71, GU13, 6P3SE....kits is not in my interest....
minorl....I mean tube amp with input for CD, DVD......and outputs for speakers.  I mean that tone control change dramaticaly sound inside in amp and it is not suitable... and sound must be realy, naturaly.  After this must increase quality of sounding of speakers and rooms, that is, IMO, Hi-End....What about if sound is changed in amp and than make gimnastic with rooms....Must increase quality of sound in series, begin from source, amp, speakers, rooms...Regulary room is not suitable for HiEnd, room for sounding make only for sounding in the end, using accustic materials.