pls see my previous post re: InnuOS Phoenix USB. The utility is very much dependent on your DAC’s clocking accuracy and USB implementation. USB is a compromised transmission format; increasingly people consider going all fibre to the streamer and on to the DAC. Since we however live in the here and now I’d try and improve the USB connection first by inserting galvanic isolation. I use the Intona Isolator with Intona reference short (!) cables for that purpose. It’ll not get you what the Phoenix can do but will be a lower cost option. The expensive bit in the Phoenix is the clock; I am somewhat disenchanted with Innuos for trying to sell us the same thing twice rather than offer separate clock entries in one unit (Phoenix USB and Phoenix Ethernet) since clocking is important in both links.
tThe reason I am unconvinced about the Phoenix USB is mainly that in asynchronous USB the DAC slaves the server to its clock; so by getting better clocking on the Dac rather than inserting another box you actually kill two birds with one stone: not only do you improve USB clocking but you also, and in my mind even more importantly improve clocking of the D to A conversion with very beneficial effects on attack, reverb and soundstage.
All told, rather than spend too much money on USB consider whether going all fibre is a future solution and if you decide to stay with USB focus on isolation as well as the Dac’s clock.