The best tube poweramp. . What do you think about ?

Old amps like Futtermsn judt asking for trouble their problems were many 
yes they sounded good but tons of unit failures. Look for a modern amp  like Ayon for example transformers are the heart of the unit , Ayon use world class Lundahl for transformers and chokes,
And  micro processor controlled to monitor each tube for optimum operating range ,then auto bias just adds more resistors in the circuit and averages all tubes in sum too much wasted energy , and no cheap sheep metal that vibrates 
thick aluminum chassis even the tube sockets are gold over solid copper ,most are cheap brass.
the spirit3 highly recommended.

even the tube sockets are gold over solid copper ,most are cheap brass.

Gold plated tube sockets are unreliable- gold is very soft as metals go; when tubes are inserted and then removed gold is scraped from the contacts of the socket. In time, the underlying metal is exposed; in this case copper. It will then blast the remaining gold off of the contact surface as it corrodes (which is does rather quickly). The result is a bad socket.

If you want reliable sockets go for a tin-plated socket. Tin, like gold, does not corrode quickly but its much harder and so the socket can last decades longer. There's no downside for sound quality either since tubes usually have tin-plated pins.

Leben CS1000P is incredible-very detailed,big and dynamic.