Preamps

I'd first try a Benchmark LA4 @ only $2.6k, specs wise it's SOTA, remains to be seen if you also like the sound (Benchmark offers 30 days in home trial). Compared to the transformer coupled Rowland i'm sure it's more transparent to the source. 

https://benchmarkmedia.com/collections/preamplifiers/products/benchmark-la4-line-amplifier?variant=1...

Closer to the stated price range I'd try the T+A P3000HV and the Chord CPA 5000 (since you have the DAVE).

Another unit to check @ at the top of your price range would be the Levinson No. 523 (the same as No. 526 but without the DAC module); it would also match impedance wise with the 625. 

https://www.marklevinson.com/productdetail/~/product/no523.html

https://www.stereophile.com/content/mark-levinson-no526-preamplifier

The Corus has a 60 Ohm output impedance and the CPA 5000 has 100 Ohm, they would be indistinguishable impedance wise into the 625's 40kOhm input impedance.