NEED HELP WITH DAC UPGRADE

Differences between quality DACs are normally swallowed up by the room. The exceptions are headphone listening and to a lesser extent, listening in a well treated room. When doing critical listening through a nice set of headphones, small differences can show up but deciding what's better is normally a taste thing. Be wary of the shill recommending a 4k DAC.   

Agree!
There's a lot of killer DACs available, new and used, in the $3k-4K range. Auditioning before buying is an absolute must. Especially when spending that kind of money. In this hobby a small improvement in SQ usually requires a lot of money. 

I'm currently auditioning the new MSB "Analog" DAC.  It easily surpasses the Bryston and most who have compared it to the new Berkeley have preferred the MSB.  I haven't heard a better DAC than the Analog.

If you want to keep your cost under $6,000, the LampizatOr Lite 7 DAC is a wonderful option.  Here's a link to my review:

http://www.ayllonmedia.com/1/post/2015/06/the-lampizator-lite-7-dac-a-high-performance-machine-or-a-bloated-beetle.html

I really like the solid warranty on all Bryston products, but with limited ability to audition you will have problems.

Some mail order places allow audition & return.  Oppo, which will have a new DAC out soon, is one.

Also start looking at mail order retailers who allow returns.