I will change nothing right now because there is synergy between all the pieces of my small speakers system and i optimized everything (mechanical,electrical acoustical) to reach their peak working level together...(it takes many months to do that)..
I will change nothing now because the pieces cost : dac,amplifier,pre-amp tube equaliser, headphone amp, powered speakers, linear power supply,conditioner are all at the same low price each pieces under 200 bucks each most around 150...
This is my secondary system for casual listening and non focussed listening...
I will change nothing in my main system: AKG K340, Sansui alpha, and Hidizs dac + file bank+equalizer... because this system is a TOP one already at peanuts cost (i tried to upgrade the amplifier and i failed the Sansui alpha is a TOP amp even for today and the K340 is very hard on most headphone amplifier...
But if budget is not a problem...
It is very easy to improve my secondary system with new TOP speakers (driven now my my Sansui alpha instead of smaller powered one so good they are right now as modified and optimized, i will replace them with 1,000 bucks non amplified speakers probably...
i dont think i can replace the AKG K340 optimized with any headphone under 1,000 bucks and by most costlier headphones for reasons i will not repeat here...
My main improvement anyway in the last months was buying a better non linear supply, a better purifier/conditioner at price lower even than the price of the pieces they replaced...
But my greatest impactful change was not buying gear ...
it was the specific grounding of ALL pieces of gear in my 2 system...(even the linear power supply, the computer, the conditioner were grounded separetely with all the other gear piece separately)
Epochal improvement...
As powerful as acoustics controls if i want to compared the change...Lower noise floor impacting my 2 systems...
THe K340 is now a king among headphones...nothing i ever own even touch it...