I've had a pair of M-Audio Studiophile AV40 speakers for almost a year now and not once have I regretted the purchase.
I bought these to replace a pair of Creative Gigaworks T20 speakers as I couldn't live with the poor accuracy, lack of clarity and tonal colouring. Plenty of people praise the T20s sound, but trust me they are not good!
The AV40s are heads above all of the multi-media speaker companies, but that doesn't surprise me as these are essentially entry level active studio monitors, not just speakers! As such they are far more detailed and accurate in their sound, in fact listening to tracks I've edited on the creative T20s is just plain embarrassing as faults I could not hear before are readily apparent.
As for volume, there's plenty, in fact perhaps too much if you are using them in the same location as you would multi-media speakers (my AV40s have never used more than 1/3 of what they can deal up). So if you are planning to use them in this way then the AV40s little brothers, the AV20s are probably better fit.
As for criticisms, the isolation from the desk could be better, but that easy enough to solve with 4 squash balls cut in half. Other than that certain harmonic piano frequencies can cause the grill to buzz, but that's the only real sonic fault to mention at this price point.