The 4000 is far superior one guy I met at a audio club bought one it sounds excellent and their latest effort ,the 5000 is better still
the taps on the transformer is just switched their is 100 v Japan ,115v N America
and 220 v taps for Europe . It looked easy for any tech sure it voids U.S warranty
but in the top5% most dependable in the world ,every part is inspected and tested
and runin for 100 hours before it leaves the factory .