I have the LA4 preamp and I had someone over yesterday to buy a DAC. He loved the LA4 and CODA #16 combo so much that he went home and ordered the LA4. He has a Pass Labs amp (maybe the 250.8).
The CODA #8 is $6K new and I also owned it and listened with the LA4. It was very good, the #16 is great.
The amp that I also loved with the LA4 was the KRELL Duo 175XD. I have seen some Duo 300XD on the used market. I sold my 175XD to buy the CODA #16. I figured the #16 would give me more power for some new speakers.
The Parasound A21+ was also rather good with the LA4. Not as good as the other amps mentioned but a great value.
I use Benchmark AHB2 monos with the LA4 and they are my fav amps. They could have more oomph for difficult to drive speakers, but I have them on not too hard to drive KEF LS50 Meta monitors.