My favorite EXTERNAL preamps for the Schoeps are in this order for EVERYTHING but Phish!
#1. EAA PSP-2
#2. Schoeps VMS
#3. Sonosax/LB's & TB's with Output Transformers
However, for recording Phish ONLY, Schoeps->Sonosax is ALWAYS where it's at for me for whatever reason! That combo just emphasizes Phish PERFECTLY IMO! And the above preamps are strictly external FWIW!
That said, the Tascam DR-70D has GREAT stock preamps IMO, and I can BARELY tell a difference between the Schoeps VMS02IB and the DR-70D Preamps! As always, YMMV
But that just goes with what DSatz stated in this thread awhile back! The Schoeps have a low ohm resistance being transformerless and sound "alike" with most preamps it's run with! That seems to be the exact case with my VMS02IB & DR-70D preamps! They both sound very similar to me! The VMS02IB is definitely a QUIETER preamp, but you'd never notice that unless recording acoustic or unamplified music! In fact, I loved the caps>KCY>+60v PFA>DR-70D preamps sound so much, that I bought  +60v PFA setups so that I can run 4 Channels of +60v PFA's directly into my 70D Preamps
That also means that I can leave my heavy-ass VMS02IB at home most nights and just have to worry about powering the 70D with a single USB battery, instead of dealing with lugging the heavy brick VMS02IB and batteries for it to run 4 channels of DAUD mics! I do love the VMS02IB sound overall, and the KCY Input is sweet, but with the new +60v PFA's and having XLR's with DarkTrain Rt Angle Stubby XLR Breakout Cables for ANY Preamp/Recorder, I sometimes wonder why I even have the VMS02IB when the DR-70D preamps are more than adequate for my recording needs, and the VMS02IB is so damn heavy?!?! The +60v PFA's and their regular, 3-pin XLR outputs basically turn my KCY>60v PFA setup into an even more compact Schoeps CCM system, but with interchangeable capsules and a single cable vs. two cables of the CCM Series
I JUST got the 2nd +60v PFA a couple of months ago, so I haven't got to run 4 channels of 60v PFA's "live" yet! I don't see myself selling my VMS02IB anytime soon, but if I start pulling kick-ass recordings with just the 60v PFA's, like I did in the past with my VMS02IB and +48v PFA's, the VMS02IB might be a goner and I can invest that $$ into a nicer 4-6 Channel deck like a Tascam 701D or DR-680mkii