You can see that the 80's have one more tweeter and 1 more mid than the 60. The 80's are rated at 4ohms, which can cause problems with some receivers/amplifiers. I don't have either speaker but the consensus is that the M80 will give you more bass and a larger soundstage. If your current system can drive 4ohm speakers you won't have to purchase anything different to run the M80. Now, there are many receivers/amplifiers that aren't rated for less than 8ohms but have no problem doing so. Denon and H-K are 2 of them.
