Just got my teac A6300 back from sam, He did his magic on this and it sounds better than brand new. I think he knows something about these that Teac didn't know. Freq response was 22 to 24kz at 7.5 ips. I think a person could do Mach 10 and not worry about resonating into their CD player or turntable with a RTR. I have a Tascam 35-2 that I am going to have him tune next.