I wanted to warn anyone considering purchasing the Quad QSP amps about my recent nightmare of an experience with this model. Firstly i would like to say i've owned a 909 since 2007, and it's always worked perfectly and never had any problems. However when i decided to purchase three Quad QSP amps (i wanted to tri-amp my speakers), i discovered this new QSP model (the 909's official replacement) is completely inferior to the 909 in every single way. I was eagerly awaiting my amps for some months, and then finally when they arrived, the horror began. All three of the QSP amps produced SEVERE distortion whilst attempting to play music. This distortion was highly evident to me, my wife and also the salesman in the hi-fi shop when i took them back. I even left the third amp sealed in its packaging so when the storeman opened it up to play the thing, he would know i had not in any way tampered with it. Suffice it to say the third amp performed exactly like the others. It's very interesting that i read someone elses review of a Quad QSP on Amazon.uk (around the time when the amp was first released), and the poor guy had gone through some similar issues to what i have now experienced (and his review is still there on Amazon.uk if anyone wishes to check that out). It would seem these Quad amps have been plagued with issues from the beginning! Some months later, my three replacement QSP amps finally arrived, and although these replacement amps were not defective, the sound they produced was not half as good as the classic 909 amp! It's also interesting that that QSP weighs about one third less than the original 909. Makes you wonder what has been replaced? And with what quality of components? But i diverse. To get back to how these 'functioning' QSP amps sounded (compared to the 909), i was say the QSP amps sounded far less crisp, less trebble and significantly LESS BASS. this was contrary to everything the reviews were saying. I was genuinely shocked at how bad these QSP amps sound. They are really that terrible. Knowhere near in the same league as the classic 909 amp (and even that was replaced with cheaped caps during the last few years of it's producing so i'm told, but at least it still sounded quite good). I wanted to put this hear as a warning to anyone considering purchasing the Quad QSP. DON'T! Or if you can't help yourself, please give it a very thorough audition before purchasing. Better still, do a side by side with the 909. It would indeed seem to be the case that since Quad has gone into the hands of Chinese owners, the brand is continuously going further and further down the toilet.