@charliee I own and love the SLP-05 and have used many amps.
For the high gain of the balanced out I recommend an amp with 20 db gain ideally, the Pass Labs XA25 was perfect. Possibly 22-23 db but not many amps have that kind of low gain.
For the single ended outs you can match to any amp- e.g. 26 to 29 db gain. Trust me on this.