0461...that's great that you have narrowed it down to the MC501 and MC1.2KW but unfortunately they will both not fit that well with your ARC Ref 3. There is a potential impedance mismatch and the place where it will be most apparent is in the bass fequencies, where the Ref 3 has an output impedance above a 1000 ohms. The input impedance of the MC1.2KW is 10Kohms (which gives you less than the minimum 10:1 and certainly less than the often desired 15:1 or 20:1 ratio between the amp's input impedance to the pre's output impedance. The Ref 3's overall output impedance of 600ohms balanced and 300ohms through single-ended connections will barely get you there in terms of the desired ratios but as I said in the important bass region the Ref 3's output impedance goes above 1000ohms. This will cause attenuated and loose bass performance most likely and will therefore muddy up the overall resolution and thicken the sound.
If you look at ARC's power amps (both SS and tube) they are all above 100K ohms in terms of input impedance. So you may have to find a low output impedance preamp to match with your McIntosh SS amps, maybe 1 of their own preamps like the C500T.
Good luck.
If you look at ARC's power amps (both SS and tube) they are all above 100K ohms in terms of input impedance. So you may have to find a low output impedance preamp to match with your McIntosh SS amps, maybe 1 of their own preamps like the C500T.
Good luck.