Transcoding - Transcoded Material

My DP has FCP 7 and a DSLR camera.

I have FCP 6 on an early G5. I've tried raw DSLR footage and it doesn't play.

He transcoded the DSLR footage to ProRes 422 (HQ). Which again does not play.

I took the transcoded (HQ) and ran it through compressor again to simple ProRes 422.

It seems to be working fine.

Since I've transcoded files that were already transcoded, have I lost any quality? Is this something that shouldn't be done?

The footage looks great. But, maybe there's something I'm missing.

Thanks.