I need advice on Dissimilar runs using XLR

No at @ghdprentice not at all go take a EE class, better yet Gene @ audioholics can help you a lot. Also give this podcast a listen, bebunks alot of this BS people subscribe to. 

https://darko.audio/2023/10/podcast-10-hi-fi-myths-busted-w-peter-comeau/

https://www.gcaudio.com/tips-tricks/cable-length-and-the-effects-on-sound-quality

https://forum.audiogon.com/discussions/do-speaker-wires-have-to-be-the-same-length-for-each-speaker

https://producerhive.com/ask-the-hive/does-audio-cable-length-matter/

The results are in.

I ran 1m Audioquest speaker cables from my solid state woofer amps. This necessitated one XLR from the crossover being 20' and the other 4'. I could not hear any differences between the L & R channel. I reversed the cables- no audible difference. I used some tracks that are very difficult on a woofer- Bozz Skaggs Because Of You. Nothing. Zero zip nada. Looks like Jeffery125 was right. 

I appreciate all the input here. I was probably OCD worried about it way too much. 

I also made a set of XLRs per the writeup Paul McGowan of PS audio

 https://www.psaudio.com/blogs/how-to/how-to-make-a-50-pair-of-high-end-xlr-cables?_pos=1&_sid=0ce5e90e7&_ss=r

I used the cables and ends he recommended and again was surprised that my Morrow Audio XLR interconnects sounded no different than McGowan's home brew cable formula applied between my Audio Research SP 15 and the ARC VT130 power amp. Just to make sure I used the "McGowan" cable on one channel and the Morrow on the other channel- then reversed them. No audible difference. I'm stunned that my $50 McGowan cable and my $500 Morrow 1m interconnects are indistinguishable. I suspect there is a LOT of BS in the cable seller's claims. If I had no budget I'd probably buy the $6,000 interconnects in the fancy wood box but since I'm not a Billionaire I'll be happy getting max value for my HiFi buck. 

@yesiam_a_pirate Wrote:

 I was probably OCD worried about it way too much. 

I agree!

Mike

I have tried both equal length and different length XLR cables and I could not tell the difference. However, this was with a preamp with plenty of drive (low output impedance) into a fairly high impedance input. It's possible that a high capacitance cable with a source that has fairly high output impedance would have a more noticeable difference. 

Keep in mind that in a studio environment, or live venue, balanced cables of wildly different lengths are used. 

I have, however, noticed a difference with speaker cables of significantly different lengths and try to avoid this. I've found that shorter speaker cables are always better and given the choice of short speaker cables or short balanced interconnects, the former is the clear winner. 

I have tried a number of different balanced cables (probably close to a dozen types). My favorite is Iconoclast 4x4 UP-OCC, but I've also had good luck with Mogami 2549 cable. The Mogami cable is much less expensive and nearly as good as the Iconoclast (in my system with my ears). Amazon sells a brand called Worlds Best Cables that uses this Mogami  bulk cable with Neutrik connectors. I recently bought four 25ft cables for $140 total. Exceptional value.

Get/make both a 1m and a 6m pair and compare