The office is located between Stockholm city and the Arlanda Airport. Take the E4 till you reach the Sollentuna exit. Follow signs to Sollentuna centrum. When arriving to the red light cross with a Statoil fuel station on left side, go straight to the roundabout in front of you, where you turn left. You are now on Tingsvägen. Keep right and after 100 m make a 90degree left turn when you see the Polyamp sign on the office building 300m in front of you. Pass that building and use the parking on that side of the building. Tingsvägen 19 is the first entrance from the parking.
Use local train from Stockholm Central, platform 15/16. Use train with direction to Märsta or Upplands-Väsby. Stations counted from Stockholm Central; Karlberg, Solna, Ulriksdal, Hellenelund, Sollentuna. The trip takes approx. 15 minutes. Use the exit as you're facing the trains travelling direction. Turn right after exiting the stairs (you're in a tunnel). When out of the tunnel take the stairs on the left side. Go to the second entrance (no 19) of the high office building on your right.
Arrival at Arlanda airport, Stockholm (ARN). Use a cab/taxi, it takes 20 minutes, ask for fixed price. There is a bus shuttle leaving for Sollentuna Star Hotel once an hour or you can take local bus to Märsta train station and from there take a local train to Sollentuna. Arrival at Skavsta airport in Nyköping (NYO). Use the bus shuttle to Stockholm Bus terminal, takes 1h. Cross the road to Stockholm Central and take the local train to Sollentuna. See by train above.