[Edric Li]

Threads like this really confuses me. I understand inverted signal, +4db, -10db, etc etc. I simply want to know what configuration will short or cause damage to which equipment, and why. If it depends on the circuitry of the equipment, why?

Say I am connecting a DAC to an amp:
1. Balanced 4.4mm output to unbalanced 3.5mm input
2. Unbalanced 3.5mm input to balanced 4.4mm input
3. Balanced 4.4mm output to unbalanced RCA input
4. Unbalanced RCA output to balanced 4.4mm input
5. Balanced XLR output to unbalanced RCA input
6. Unbalanced RCA output to balanced XLR input

with the wiring diagrams below

 

[dunring]

You can plug a balanced headphone into a single ended amp using an XLR to 6.35mm adapter and it's fine. You must never do it the other way around or the amp can/will short out. It's why places like in Etsy do conversions of Beyerdynamic headphones to balanced, since you can use an adapter on them. Much more practical to just preamp to a $100 Heresy and sell it if needed down the road. The converted headphones I've seen on eBay never sell for any more, conversions not a very good investment.

 

[Edric Li]

You can plug a balanced headphone into a single ended amp using an XLR to 6.35mm adapter and it's fine. You must never do it the other way around or the amp can/will short out. It's why places like in Etsy do conversions of Beyerdynamic headphones to balanced, since you can use an adapter on them. Much more practical to just preamp to a $100 Heresy and sell it if needed down the road. The converted headphones I've seen on eBay never sell for any more, conversions not a very good investment.

But why does connecting the L- and R- of the amp create a short circuit?

 

[jasonhanjk]

But why does connecting the L- and R- of the amp create a short circuit?

Because they are output. L- is the invert of L+, R- is the invert of R+.