awakeningosirisThe only difference will be if your amp has both single-ended and balanced outputs, in which case the balanced output will have double the output impedance of the single ended output which could have a very insignificant increase in midbass on the HD650.
Other than that not much.
xxicrimsonixxAlso balanced cables usually can run at higher voltages than single ended. Balanced has a ground for the positive and the negative where the single ended shares a single ground for both. There will be more separation without having a shared wire for both drivers, and also in high impedance headphones a little more bass with balanced because the higher voltages can help the low frequencies travel more effeciently to the driver, allowing it to play with more volume in that range.
But to get the advantages of balanced you have to have a balanced dac (cheapest one you can get is the Scarlet 2i2, meant as a microphone interface but has 2 excellent dacs inside of it, one for each driver) and a balanced amp. I don't know what the cheapest balanced amp is so can't help there but then you also need a balanced cable. The difference is definitely noticeable AND measurable.
However it's a lot of money to spend on a noticeable but not game changing experience unless you already have most/all of the equipment.
By the way the cheapest I've found the 2i2's is Reverb.com
That's where I buy all my microphones, super helpful staff as well.