Lower volume with some XLR's?

Ar you using all three pins in your home made XLR?
Generally the standard for RCA(single ended) vs XLR (balanced is about 6dB..
So I would say you wired your homespun XLR wrong.
The calbe must have three wires to chang it to XLR.. If it only has two wires, ore the central wire and ground.. No way will it work as a proper XLR passthrough.

If the wires are corrently used, and the cable has at least three wires.. then one of the 'sides' of the balanced is not working. Either wires wrong, a short or open wire...

I second Elizabeth's comments. Although your statement that the cable type you modified is the same cable type as the one that was factory terminated with XLR's would seem to imply that the cable you modified has two signal conductors plus a separate shield or other ground conductor, and it would therefore be suitable to use.

Given that, and assuming you've compared the two sets of cables at the same location in the system, the volume difference is almost certainly 6 db, and the cause would be either an open (missing) connection on one of the pins, or a short between one of the two signal pins (pin 2 or pin 3) and ground (pin 1). A multimeter would allow you to quickly determine which of those possibilities is occurring.

Regards,
-- Al

DUH!! I finally realized what I did. I crossed the ground wire between the input end and output end. I was so fixated on orientation when looking at the pins, that I wired the female ends the same orientation when looking at the holes. This obviously moved the ground from one side to the other from input to output. I'll rewire them and all should be fine. Just wasn't thinking that the orientation would be the opposite on the other end of the cable to keep all contacts in the proper place.

It is easy to make a mistake with wiring XLRs. The male and female hot and return must be wired inversely.

I made a coloured exploded diagram to help me keep this straight. Thoroughly confusing.