I used to use a Krell KSA 200s sometime back with my Watt Puppy 6s (with the new tweeter) and although the system is not the same, it probably sounds somewhat similar to your current setup. If so, there is plenty of room for improvement on the amp side.
I'm using a pair of YBA Passion 1000s now and the difference between now and with the old KSA200s is night and day. Yes, it's not tubed (but it has a tube-like sound) and the price is more than your stated budget. Just letting you know that there's plenty of improvement waiting if you make the correct choice.