There’s no good adaptor solution that is better than your current set up. Besides hiring an electrician to run a new cable for you I encourage you to find a Wifi analyzer for your phone or laptop to check the signal strength and also make sure you are an uncongested channel. Also, use 5GHz instead of 2 GHz if you have a strong enough signal. Fewer people use it and it has better bandwidth.
Keep in mind that audio requires very little bandwidth. A good wifi signal has many times more bandwidth than you’ll need unless you have many other users in the home.