I use a MC352 and I have gone through several pre amps, here I will recommend two tube based because tubes will inject some real palpable sound with texture and awesome color with beauty of tone.
The Manley Labs 300B would be my first choice. Has a very low output impedance so it will drive those 601’s no problem. RCA only. If you like headphones, your really in for a treat as well.
www.manley.com/hifi/neo3br
The other very high on your consideration list should be the Modwright LS300
http://www.modwright.com/products/ls300-balanced-tube-preamplifier.php
Again very low output impedance can drive those 601’s no problem. Plus you can use balanced cables if thats appealing.
I like the Audio Research as well, but these two I like a little more:-)
Matt M
The Manley Labs 300B would be my first choice. Has a very low output impedance so it will drive those 601’s no problem. RCA only. If you like headphones, your really in for a treat as well.
www.manley.com/hifi/neo3br
The other very high on your consideration list should be the Modwright LS300
http://www.modwright.com/products/ls300-balanced-tube-preamplifier.php
Again very low output impedance can drive those 601’s no problem. Plus you can use balanced cables if thats appealing.
I like the Audio Research as well, but these two I like a little more:-)
Matt M