My wife and I bought an old semi-detached home, and were very pleased with everything except for the soundproofing between us and our joined neighbors. After some research, we landed on GVC Contracting, who did a complete rebuild of the adjoining wall - taking down all drywall, replacing the insulation, and rebuilding the drywall on resilient channels, with two layers connected by "green glue" suppressant adhesive.
Greg and his team were superb - they were timely, polite, honest, hardworking, and fair. They consistently left our place in clean condition at the end of every day. Some quirks of our old home slowed down progress, but they were happy to work overtime to keep close to the original timeline, and honoured their original estimate. We quickly came to trust Greg and his workers, and were comfortable to leave them home alone to work. The quality of work was also great - a very high attention to detail was shown. At the end of the project, they insisted that we hold back a portion of payment for a weekend to make sure were were happy with everything, and that there were no little touch-ups necessary. I would highly recommend GVC Contracting for any soundproofing project, or for any other renovation work that they provide. Really A+ service.