I was looking over the specs of the 4k and noticed this about the Phono input:
Inputs/Outputs
Rec In LINE/MIC L/R:
1/4-inch stereo phone/XLR Combo jack, balanced
1/4-inch phone: Imp. 18kohm, 24dBu max. XLR, Imp. 6kohm, 22dBu max.
Rec In PHONO L/R: RCA-pin x 2 with RIAA EQ, -24dBu max...