Parasound a21 upgrades

I'm running RME ADI-2 dac directly into the amp. Also tried with my upgraded Joida Pre and prefer direct for sure. I only do digital so I see no need for a preamp. 
I tried balanced and unbalanced and heard no difference which makes sense since I believe the A21 is not truly balanced. 

Thanks Eric,

Just for my own curiosity what would be an amp that you would see as a clear upgrade to the A21 not priced in the stratosphere. Similar power specs let's say 6k or under new price. 

Thanks all,

As I said I am very happy at the moment with the stock A21 so won't be upgrading in the near future. I'm sure at some point the bug will bite! Ussually sooner than I'd like. 

I may look into the hifi tuning fuse. I am ussually very skeptical of such things but for 100 buck would not be out a whole lot and I can make my own determination. 

@jdub39 
I agree since I very much like the basic sound signature of the A21 the JC5 may be a clear path. At least from a risk standpoint. In your mind was it worth the extra cost? 

Thanks for the suggestions. I think I will take Eric's advice and leave it alone. I do really like the amp. Added dedicated 20a circuits today. Nice improvement! 

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.