I have an unmodded Transporter and thought I should comment. My system sounds better than ever before. I am using the Transporter directly into my McCormack DNA-500 via Outlaw RCA interconnects. The amp is connected to my Salk Veracity HT3's.
I had been using a Bolder digital only modded SB3 with the Basic rev 1 PS with film caps. The modded SB3 went to my Parasound prepro for DAC/preamp function and then to the amp and speakers. It's obviously not an apples to apples comparison but the Transporter is worlds better. The detail is there but there's improved imaging and instrument separation. The bass through the treble is more realistic, balanced, and musical. My Salk HT3's sound the very best that I've heard them and they are wonderful speakers.
Now, I also think my present set up is superior to my original modded SB3 rig and this is more of a fair comparison. I originally had the Squeezebox digital out going directly to an Aberdeen modded Tact which served as DAC and preamp with much lauded room correction. I used the same amp and speakers and I was never completely satisfied. The sound was better than the Parasound set up but I didn't enjoy it nearly as much as I do the Transporter. The Transporter just sounds great. And I have to admit, the display is really cool.