High expectations, slightly disappointed

First of all: I hear my music exclusively through headphones. So the hearing impression is of course a completely different, as if quality speakers are connected.
25 kilos, as well as the postman had something like this. Many marathoners comes less breathless finish as this good man the two flights of stairs. Even while unpacking we noticed the high quality workmanship of Yamaha AS 1000. The first hearing impression was a bit disappointing. The Yamaha emphasizes the higher frequencies, the bass is good effect but the centers are a bit thin. So I joined my other amplifiers in a series and the Yamaha as a terminal to. So I come to the growling sound, to which I got used to. Now the Yamaha demonstrates its great strengths, because what formerly was something in sonic mush, is now audible and the bass is much more differentiated. I do not regret the purchase and recommend the amplifier.