I received my Hartke HA4000 bass amp on Friday and these are my initial impressions It is heavy. About 30 lbs heavy. It has the appearance of a straight power amp (not a head), but with more controls. Very solid and well built. A lot of control over tone. Too much at first. My first impression was that I did not like the sound at all. But it does require some work setting up your sound. After playing around with all of the controls, I finally found my sound. Oh man, did I ever. The thing that struck me after I got my sound dialed in was that the 4000 solid state amp sounds like a tube amp. That distinctively warm, powerful, fat low end. It really pumps out the low E and B string tightly. I haven't played through it with my band yet, so I can't give it a total thumbs up just yet. But it shakes my house at pretty low volume settings and still maintains a very clean sound when turned up beyond tolerable with loads of headroom to spare. I can get a clean or dirty tone with it. I prefer scooped mids with a hi-fi tone, but one can adjust the mids to be anything you want them to be. The EQ allows for very fine tuning of the mids with Low Mids and High Mids that can be adjusted for specific frequencies or wide bands of frequencies. A lot of tone and power, with a tube like sound in a $500 solid state amp. Ill let you know more as I play more with it. If anyone has any questions feel free to ask, Id be more than happy to share what I know about it.