I sometimes plug my Amazon Fire 7 tablet into my hi-fi to listen to Spotify (the free version with ads) I use the headphone socket from the tablet and plug it into my main amp. The sound is good but I was wondering if it is possible to use a DAC and if so could I expect any improvement in sound quality? My amp is a Marantz PM6004 and only has analogue inputs. I don't know much about digital audio.