Parasound a21 upgrades


Bought a lightly used 2 year old Parasound A21 some days ago. It has exceeded my expectations for sure. Right up my alley warm mids and non aggressive highs but also dynamic and tight with lots of headroom. 
Are there any mods that are reasonable to do to these amps? Fuses etc. Can the bias be safely increased to add more class a watts? 
Also have there been any changes over the years? So is a 2 year old A21 the same as a 15 year old one? 

Thanks
mofojo
Right up my alley warm mids and non aggressive highs but also dynamic and tight with lots of headroom.
What more can you want, John Curl's not an idiot, if he thought a "snake oil fuse" would make a difference for the better again he would have put it in.
Don't listen to these "fuser twits" here, they have absolutely no idea, and that's about their technical skill limit, to change a fuse, so that's all they will do and comment on.

Cheers George  
Agreed. Like I said I very much like the amp. I'm sure multiples in cost would likely bring an improvement. I'm good to go for a "long" while. I think. Dedicated lines today are a big improvement"no sh.t. and the longer I listen not snake oil. I had nasty s**t on those lines. 
Ha  ha says one twit . 
In a thread on Audio Asylum , we had a great discussion a few years back with Mr. Curl who said if given the choice he would've used silver fuses in the  Halo amps, I used the Silver Star in my A21 and the results kicked up several notches in refinement across the spectrum , there was a reason I kept the A21 around for 12yrs , it just flat out sounded so good!
I have been an A21 owner for about 9 years now, lthough I upgraded two years ago to a Plinius SA-103. It was almost three times the cost of a good used A21 at the time and still well under your future budget.  Even though the SA-103 can be switched into full time Class A mode I still find myself listening in Class AB most of the time.  It was a a worthy upgrade.  I had been driving the A21 for those first 7 years with an Aesthetix Calypso.  Last year I updated the Calypso to the Signature level along with a good set of NOS 60’s and 70’s tubes.  I feel no desire or need to update either the amp or preamp.  
jdub3 In a thread on Audio Asylum , we had a great discussion a few years back with Mr. Curl who said if given the choice he would've used silver fuses in the Halo amps, I used the Silver Star in my A21 and the results kicked up several notches in refinement across the spectrum , there was a reason I kept the A21 around for 12yrs , it just flat out sounded so good!
Prove it with a link to it, AA retain all links.