I love mine [Tonic] and use it everyday on vocals and acoustic guitars. Not one time have I ever been disappointed or longed for something different.
I have two Tonics and they are really nice EQ's. Very tight bass! I love it for that, and the mid range is extremely versatile. You can cover a lot of frequency range with the x10 switch. I'd say it's a pretty clean EQ with a tight and detailed sound, but not harsh at all. I love mine. I mostly use them for bass but I've had great success on drums, acoustic and electric guitars, and vocals. That pretty much covers all bases. I do wish they were 4 band EQ's but c'est la vie. That's my only complaint.
P.S. - I really love the feel of the knobs. They are large and have the perfect amount of resistance for me. Also, the indention at 0 is great for making sure everything is centered and for gauging where you're at when not looking while tweaking. Small movements can make a big difference. Very cool EQ's.
This eq is really a joy to use. You can really add a lot of silky highs without things sounding harsh. The mids sound really rich and the bottom end is super tight. Problem is now I hate eq pluggins!
I must say, the frequency selections on the high and the low bands (5k/11k and 60Hz/120Hz respectively) are IMO extremely useful and very appropriate for many sources. Never felt like I was yearning for more options frequency wise. I've tried several nice 500 series EQ's, but if I had to own one and one only, it would be the Tonic. I can't imagine how much two of these beauties would rule on a full mix. I think the Tonic is an absolute steal when considering the features and superb sonic quality.