Can I truly get the best sound using an AVR Pre... Yes I know about room correct Andrew.... And most of the time ACR Pre's a very expensive.
Of course you can and it gives you a lot more options.
There is so much nonsense floating around about this. Any 50 cent op amp will have better performance than just about anything else in the system. So the quality of an AVR is its analog circuitry and the processor. You actually have to work hard to make a preamp sound bad. However in analog mode, head room can be an issue. I have two Marantz pre/pros. I have only bench tested one, but it has loads of head room.
These offer balanced connections if you want them. However balanced inputs are all about interference rejection, not about improved sound quality. The xlr balanced connection was developed years ago in professional circles to deal with noise in long cable runs in electrically noisy buildings. The signal positive and negative connections float above ground. The idea is that the signal cables pick up identical interference. So if the input is balanced like in a matched differential J-FET arrangement you get excellent common mode rejection. There is a common misconception that balanced arrangements help with ground loops. They do not.
So if you do use balanced circuits the most important place to have common mode rejection is at the input.
There is a highly erroneous view on these forums that balanced circuits are inherently better than unbalanced ones. The only place this is really true, is with common mode rejection HF signal loss in long cable runs and above all in the output stage of power amps. Only balanced power output stages are capable of high power. The only output stages that are not balanced are the single ended triodes. However, no matter what the enthusiast with highly active imaginations say, they are lousy low powered amplifiers.
Now the big area where balanced circuits are not superior is degradation over time. All balanced circuits are isomers of one another essentially, that is to say they most be perfect mirror images. If they are not then the sine wave is not symmetrical and a potent source of distortion.
So this means that all the components have to be hand matched. This is why they cost so much. So you get your shiny new amp balanced through out, that you pawned your wife's diamond ring for, and it's audio nirvana, and measures fine too. But we all know what happens over the years. Those resistors caps and solid state devices age and wander from their original performance. The problem is there is no guarantee our mirror images will age the same and they usually won't. So imperceptibly to the user distortion levels rise over the years bit by bit.
So that is why in my view you don't want anymore active balanced circuits in the audio chain then dictated by application.
The only circuits I know that solve this problem are the feed forward circuits of Peter Walker and Nelson Pass. These amps, have a very good low powered class A amps, that feed an error signal to the Class A/B biased dumpers, which can be biased heavily to B and run cool. Performance is class A. However, there is another benefit, they correct out of balance conditions in the output stage. So confident was Peter Walker in this, that he never bothered matching his output transistors. He personally demonstrated to me and amp that worked perfectly with the output transistors mismatched by 30%.
I follow the DIY community and in the last 12 months or so, there has been a resurgence of interest in this approach, with new circuits appearing on the forums. So may be we will start seeing more commercial offerings of this approach other then from just Quad.
