Determine what noise sources you need to soundproof against. If you plan to use the room for recording, soundproofing is vital. For example, if your mixing room is located in your basement, the noise from your home's heating system could be a problem.
Soundproof the room. For the best results, rip out the old walls, ceiling and floor and replace them with special soundproofing materials. A less expensive option is to staple acoustical tiles or soundproofing foam to all the surfaces in your room. Also, install soundproofing materials around doors and windows to minimize sound leakage.
Ask an electrician to check your wiring. A common source of interference in audio signals is ground loop hum, which is caused by faulty wiring. Also, bad wiring could cause damage to your expensive audio equipment.
Set up all your equipment. Speakers should be at ear level and form an equilateral triangle with where you sit (both speakers should be the same distance from you and each other). Moving your mixing desk to different locations can drastically change the sound of the speakers, so try different spots until you find the one that works best for you.
Use balanced audio cables, such as XLR or TRS (Tip Ring Sleeve), for long-distance connections between audio devices. Balanced audio cables eliminate interference caused by nearby electronic devices or your home's wiring. If you have built a separate booth for recording, consider using an XLR wall plate to route cables through the wall.
Test your equipment and adjust the room's reflective surfaces to achieve the perfect sound. For example, a recording made in your new studio may have a tinny reverb caused by sound reflections in the room. To fix this, try putting pillows in the top part of the corners of the room. If the room sounds dead, try removing some items to create more reverb.