...changing the Tubes on the Jadis DA50 worth it ?

I am considering changing the Tubes on the Jadis DA50 , what can I expect is it worth it ?
It looks like it will run around $350 and up.
Alternatively I could use that towards a better D/A.
I want to improve my my Jadis DA50 integrated and Legacy Illusion speaker.
(Illusion is somewhere between Focus and Whisper) set up.
I tried different cables not much improvement.
I used my Legend D/A (now von Gaylord) from a different system and had a big improvement.
However that D/A is no longer available and the current D/A model ($13K) is bit much for a second system.

My other sources are a the HK HD7600 (kind of bright on the up frequencies and no emotions),
PC with Headphone out (seems okay), Nakamichi Dragon , Sansui TU9900 and a never used in over 25 years J A Michell hydraulic pretty turntable (just like the looks of it).

Mainly will listen to CD's ,...maybe more Internet stuff in the future, ...maybe at some point records but most likely not.

any advice would be great.
Depends how old the tubes are. If too old you should replace or get them tested.
I have tried KT90, KT88, 6550 and 6CA7 on my Jadis JA30 mono amps (should be pretty similar to your amp) and honestly, there is not a huge difference between the tubes in my amp, even though they are said to be very different from each other. The smaller tubes doesn't normally need to be replaced very often, every four or five years or something, maybe more, depending on how much you use the amp of course. Four KT88's shouldn't be too expensive, like $250 (Genalex Gold Lion).

What tubes do you have at the moment?