dude, my lead guitar player has been using a TSL 100 for quite some time now, and it's a great amp for thrash/speed metal and anything less than that. one piece of advice: USE THE CRUNCH CHANNEL ! ! ! ! ! seriously, the crunch channel has PLENTY of gain for thrash metal rhythm, and has a certain bite as well as a growl that's very unique. certainly different from my jcm800 2210, but not exactly worse. the lead channel isn't the best for metal rhythm, though, and i can see why people tend to call them mushy and fuzzy POS. it's not the best amp for leads, too. my 2210 just "sings" more than the TSL ever will, and that's with less gain.
but once again, the crunch channel is great. actually i've considered getting one for a few times. the dsl is close, but not really the same (i used a dsl100 for 3 weeks on tour. channel 4 (hi lead) is crap, channel 3 (low lead) is decent). it's very tight, with good bass (not vht, bogner, or mesa bass, though), and a nice edgy feel. in comparison to a 2210 it's darker even with the presence way up, and has more bottom end.
one last thing, it gets all nasty and fuzzy even on the crunch channel when the tone shift is engaged. the deep CAN be useful at low volumes, but it just too much at gig volumes.
ok, enough OT. regarding the powerball....i don't like it. sounds solid state to my ears, with a very unpleasant high end - like all ENGLs. i've played one show with an powerball, and owned a blackmore for quite some time. both shared a certain thin sound quality. TO MY EARS, they have a lot of bass, but a huge lack of mids, especially low mids, which makes them sound thin when cranked IMHO. add the unpleasing, rather abrasive highs to that, and you'll understand why i sold my blackmore and got a 5150
on the other hand, the ENGLs have a very clear sound, thats for sure. most likely due to the lack of "muddy" low mids and the "glassy" feel of the high frequencies. but then again, i don't want a really clear sounding amp, that just does not punch in a live and loud gig setting.
just my $0.2 though