Soundproof wall between adjoining house

I live in a townhouse that has attached units on both sides. One of the attached units has its family room right next to my family room and I hear their TV, stereo, talking all the time. I'm trying to reduce the sound coming from that wall. Yesterday I tore down the existing drywall, which was 5/8" and was surprised to see insulation in the interior wall. I thought I was going to need to insulate it. I was also surprised to see a resilient channel used on the other side. I thought both sides were nailed into the 2 x 4 studs. My side was. The wall is about 16' x 8'. I installed 28 whisper clips, 25 gauge hat channel, two layers of 5/8" sheetrock with about 2.25 tubes of green glue between each 4 x 8 sheet. I also used putty pads on the adjoining walls outlets and green glue sealant around their wall and mine (including the 1/4" perimeter of my wall, outlets and in between the seams of the new drywall. I was careful not to short circuit the decoupling as has been mentioned in other threads. I also overlapped the seams of the two layers of sheetrock. I'm letting the sealant cure before taping and finishing the wall. So far there is a difference in the amount of sound coming through the wall, but it's not as much as I hoped for. I'm wondering if it will make noticable difference if I add one more 1/2" layer of sheetrock with green glue? I know there are flanking issues but it still seems there is noise coming directly through the wall, especially when I put my ear up against the wall. I know it would be more effective if the source side is soundproofed, but that is not an option. I'm skeptical adding another layer of sheetrock with green glue will help much in my situation. Any advice will be appreciated.

Update: As the Green Glue compound cures there seems to be even more improvement in sound reduction. I'll wait about a week before deciding if I should add another layer of sheetrock. If I'm still not happy with the amount of sound I hear I guess I'll try another layer. It can't hurt anything except my wallet and back.

Thanks Ted. I decided to not add another layer for now and to concentrate on soundproofing the kitchen wall, which is next to the family room. I will need to remove my counters and cabinets and I don't want to alter them too much. So, I was thinking of trying QuietRock for this wall so that I don't lose any space (replace 5/8" sheetrock with 5/8" QuietRock). The 5/8" QuietRock seems to be very expensive. Lowes has 1/2" QuietRock for about $38 a sheet. I was thinking about trying two layers of 1/2" QuietRock and hoping I could reinstall my counters/cabinets with slight adjustments. Any thoughts?