Upgrade from Apple TV??

From my computer I stream an Apple tv to my Mcintosh MX 134 and am wondering if there is any other products out there that will improve the sound quality. It's actually not bad but I'm just wondering if anything has come out to blow it away. I don't know if I understand DAC's and all that yet and am trying to figure it out. I currently run my ATV via toslink to a digital input of my mx 134 so I'm assuming the 134 is doing the digital conversion. Would I be better off trying an outboard DAC and running it into one of the analog inputs?? I can't find any info on what dac is in my mx 134 but it's gotta be 10 years old by now. I don't want anything I have to directly plug in as I like the wireless airplay function.