Is It Worh Modding An Amp

If you have to ask then probably not. 

I had Ric Schultz mod my GaN1 and it sounds terrific,  but if I had to sell it I wouldn't recover any of the $500 the mod cost.  It's a risk.

I'll add some more.

If I need a repair of any precious equipment I know techs who only will replace non-working components and touch or re-touch nothing else if everything else is in tact. 

I've repaired already several vintage and modern components at reasonable prices paid mostly for labor and diagnostics and rest little for parts and their quality work brings many units back to original specs like fresh new strings on guitar or violin. 

They don't offer any upgrades for the sakes of keeping solid reputation. Far more than often those upgrades don't satisfy customer and require lots of uncreative labor. Real pros would never advise you to fall on that upgrade bait.

@treepmeyer Ugh. I sent something to Ric once and he sent me back garbage. Horrible soldering, bad attitude and bad treatment of my materials. Avoid this turkey and learn to DIY.

Give it a shot if you’re willing to gamble. I had a Conrad Johnson cav45 v2. Bought it from a guy that sent it back to CJ and did the SE upgrade which from what I understand is just rip out cheaper caps and add Teflon caps. He said it was a large improvement over stock caps. I loved that amp. 
 

Long ago had an Exemplar Audio modded tube Denon 2900 that was one of the best cd player I had ever heard so good I bought his newer Oppo version. I also had a chance to hear a stock Denon 2900, stock sounded bad next to the modded player. 
 

I was in your place once I had a Bruce Moore preamp sitting up not being used took out signal caps added some Jupiter’s and better resistors. Really made that amp shine for what it was. You just need to figure out what sound you want from V Caps to Jupiter and everything in between. Then there is new wire better resistors, RCA jacks it never stops. I think you can make that amp sound better if you don’t buy mismatched parts, beware.