The preamp in the MA6100 is adequate, but hardly world-class. I have had one of these for 20+ years, so I know it well. For line source it's fine, but the phono stage is somewhat weak and the bass tends to be a bit woolly. If you have no need for phono, then let your ears be your guide. If you like the sound, why spend more?
The MC2002 can sound quite good with a more modern pre. Preamps are an area where modern designs really offer big improvements in sound quality and especially lack of noise. Your choice depends on your source (e.g. do you need the phono stage) and budget. I used an Audible Illusions Modulus pre with my Mac amps, and liked the combo. You often see them here for $600-$1200 depending on model and whether they have the MC phono stage.
Hope this helps!
The MC2002 can sound quite good with a more modern pre. Preamps are an area where modern designs really offer big improvements in sound quality and especially lack of noise. Your choice depends on your source (e.g. do you need the phono stage) and budget. I used an Audible Illusions Modulus pre with my Mac amps, and liked the combo. You often see them here for $600-$1200 depending on model and whether they have the MC phono stage.
Hope this helps!