A few days ago, I had the chance to compare my Ashdown MK500, ABM500 Tech 21 Character Bass VT, sansamp bass driver and 70's ampeg svt into my bergantino nv610 side by side. Here is the truth of how they sounded. Vintage SVT-Pros-This amp is pretty much what everyone who has used it says. It is very punchy, loud, breaks up perfectly and produces the kind of sound that works great in a live band. Cons-it's heavy and it may actually have too big of a tone in certain horrible sounding rooms. Ashdown ABM500- I would know this amp in my sleep from having played so many gigs with it. This one gets pretty darn close to the overdriven svt tone. The volume is about the same as the svt until they both start to break up, then the svt can go alittle farther. The abm is lighter and would make some svt guys happy but it's much more versatile than the ameg. Cons- it's a dark sounding amp that could use alittle more top end. Ashdown MK500- This is my newest amp and I've played about 10 gigs with it. The tone pics up where the ABM leaves off. There is much more top end than the abm series and an even thicker mid-range. This is my new gigging amp because it has those few extra qualities that the ABM was lacking. This is a subjective thing of course. Sansamp Bass VT- This thing through a power amp or in the effects loop of an amp is everything that the bass driver promised but didn't actually do! The overdriven tones on this thing are very close to the 70's SVT and when combined with an amp or eq can sound very convincing. Sansamp bass driver- I just hate this thing. There are some fellow tb'ers who swear that this pedal can get the old ampeg tone. If you were in the same room with me comparing all of this gear side by side your answer would change. Tech 21 should be sued for slander by claiming that their product produces such a tone! Just a lie. I learned that my MK500 into a berg nv610 actually sounds more like a vintage svt than not. It's the truth. Through a tweetered cab, I am positive that this would be different. Up until the point of power amp breakup, they can sound very similar and the output is pretty much the same. The ampeg being tube, of course has a slightly looser bottom end. At a gig, you would be hard pressed to tell the difference. If you want the 70's SVT tone, here his how I ranked your choices. 1)Buy a 70's SVT 2)Try an MK500 3)An ABM500 will get you close but could use some top end. The bass VT in the effects loop of this amp will get you very close! 3)The BAss VT into a PA will probably get you very close to the sound of a miked svt. 4) The sansamp bass driver sounds nothing like the 70's SVT in any format. It just sounds like crap when compared side by side to the other listed products. I hope that this will help some of you guys out and I hope that you will not be upset that I called the SABDDI a lie. You may like the tone that it produces, it just doesn't produce the sounds that it claims. My only regret is that the batteries in my BOSS Micor BR were dead and I couldn't get a recording of the trials. If I get to try out the guys svt in the future, I'll record them. I will likely be getting an SVT-II non pro shortley and may be going back to visit the guy with the blue line. That thread should get some hits!