Your journey with lower-watt tube amps -- Can a kit be good enough?

@bruce19 There's a kind of ceramic cap called an 'NP0' (for Negative Positive Zero) which can sound surprisingly good. They are available with leads and in the value you need, are about the size of a small bead. By ceramic cap standards they are expensive, costing a few dollars each. You might look into them; we've compared them to a number of high end coupling caps and heard no difference. I don't think they are available in values above about 0.1uf. But they are available in Voltages as high as 630V. You only need 50v though so the part will be tiny. Here's a link from DigiKey:

https://www.digikey.com/en/products/detail/murata-electronics/RDE5C1H273J2M1H03A/10703951

@atmasphere 

Thanks again! You mention using them as coupling caps. I'm curious might they also work well as coupling caps in my Elekit TU-8900 kit or other sets with 0.1 uF coupling caps with say the 0.1 uF and 1kvdc rating? I built it with the stock coupling caps figuring I might try the expensive type later, but at $4 apiece these are a much cheaper experiment than Audio Note copper or silver caps.

I hooked up my Dynaco ST-35 to my speakers and did some listening. 
97 db speakers -- JBL 16inch woofer and Beyma AMT tweeter.

HEARING: 
Very strong grip on bass. Amazingly good. 
Mid range less warm, intimate than I expected. 
Highs pretty clear, though perhaps some slight roll off. 

Overall, there is a slight lack of finesse, smoothness in the mids and highs that I am looking for in a lower-powered amp.

I think I'm not hearing this amp at its potential and it may be due to the tubes it came with: 

Sovtek 6BQ5 power tubes (4)
Sylvania nos 12DW7 pre-amp tubes (2)

If anyone has suggestions for good alternate tubes for this amp, I'm all ears.

@hilde45 I'd go with a set of JJ EL84s before Sovteks or for that matter any Russian made version.

Have the tubes been tested? If any are bad all bets are off.

If you have level controls on your speakers it might be a good idea to run pink noise through the system and using a spectrum analyzer app on your phone, adjust the controls slightly for best results. This amp has a lower output impedance than any tube amp (such as an SET) that runs no feedback so if your controls (if you have them) were optimized for an SET they won't be right for this amp.

Your amp in the photo looks fairly new. Apparently there's a resistor option on this amp; do you know which kind your amp uses? It looks like they might be the carbon film resistors. IME the metal films sound better.

If the amp has been sitting unused for a while or is brand new, it may need some break-in time.

I doubt its actually rolled off- this amp has full power bandwidth well past 50KHz.

Thanks @atmasphere. I need to check into those things and I have a friend/tech who can help.