Swapping Kt88 tubes on muzishare x7 for Kt150

Stick with the tubes your amp is designed for.

You won't get any more power. You won't extend the bass at all, and you run the risk of destroying your amp.

Filament current is higher with the KT150 over the 4 tubes it could be as much as an extra amp of current. KT150's also require either higher voltage or higher current to work properly. Anybody tells you there was an improvement likes to listen to distortion. They also require a much lower impedance drive or they could go into runaway. They also may not physically fit.

As mentioned, your amp is probably not the problem, but room, speaker placement or characteristics of the speaker itself.

No, not with your X7 I'd suspect.  Stay with KT88s.  Here is why...one other thought.  

@hvuck did you happen to notice your X7 amp designed for KT88s weighs 22.5kgs?  Now compare that to the new Muzishare X10 amp designed for KT150s, weighing in at 35kg. Wonder why there is a weight difference b7 between your X7 and the X10 model amps?  Worth researching more, this may be a sign. Bigger transformers, maybe.  

The KT150s can operate with higher plate voltage which typically requires larger and heavier transformers. Seeing this trend over the past two years with amp designers now coming out with weightier amps to run KT150s properly, in their window of optimum operation so to speak.   

RE: KT150s

My amps are designed to run KT150s, sometimes they can be so clear and transparent, and while it sounds great with a little more low end, there is more top end too - ruthlessly transparent some times. Gives the perception of less bass sometimes too. Totally neutral.  Some love this.   There are times I wanted to go back to a KT88 sound for added midrange warmth. Ended up with KT120s as my alternate set. If you must, maybe sell your X7 and buy the new X10 which runs KT150s natively if you must have KT150s.  Another angle to your question.     

Oops, we have 2 threads going. I posted in the other thread. I said no. Run KT88s, I like the Gold Lyons. Other than that you'll have to change your system. Subwoofers maybe? 

Depends.

Each KT150 draws 400ma more heater current. Can the mains transformer handle it? If the winding is 12.6V (tubes in series) then maybe, but if the winding is 6.3V then you need 400ma per tube.

Is that amp cathode biased? If so, then the KT150 will draw down to 34 volts, and going to max idle current of about 140ma per tube. Can the mains transformer (designed for the KT88 with an idle Class A current of about 85ma) handle it? Probably not.

What about the output transformer? You need at least a 70 watt P-P xfmr to handle the KT150 at Class A. That nearly double the Muzishare's 45W OPT's

If the amp is fixed bias, then the KT150 will be throttled back and you will not get any extra power. You can use it with no problem. Can't say what it will sound like, I know from experience that running Class A at less than 70% dissipation takes the life out of the sound.

Going to a KT150 requires an amp designed for a KT150. May work, but  no telling what it will sound like.