balnanced line stage vs ad811 based preamp
I recall Walt Jung has published a number of articles along the lines of this preamp you are referring to and the idea is quite interesting.
But your question is a a bit difficult to answer and I would suggest that from practical experience the opamp combination may sound detailed in the highs and fast, may also be dry and lifeless, a processed sound.
Some time ago I conducted some subjective comparisons for a dac buffer and line stage with gain using a variety of opamps.
The fact that they all sounded different in some way suggested that none of them were correct!
Why this is is even more interesting?
The Balanced Line Stage and chip opamps are from two difference schools of thought.
Opamps are usually very complex circuits with many tranistors/ fets etc, and have all sorts of funny topologies to provide whopping open loop gain , low noise and maybe low distortion.*
They nearly all require feedback to contol gain and reduce distortion and need external stability capacitors in some cases.
However, to the horror of many audio users, they are surpised to find most chips only provide piddley levels of true class A drive, only a fraction of a milliamp in many cases and they then operate in class B (this is a fact). Yuck!
Some recent chips do however have nifty distortion cancelling topologies, but they are not class A devices!
The better applications like Headrooms opamp headphone driver use Case A buffers to counter this , or you can try and bias the chip into class A with a current source.
The problem here is most chips will go up in flames over 0.5 watts disipation.
It is reasonable to assume SE class A operation is preferable for at least a preamplifers, so why bother with chips in the first place.
Manufacturers use them because its cheap and easy, and Mr Average punter may never know better.
The Pass Balanced Line Stage, as you are now doubt aware is almost the direct opposite in approach.
The circuit is simple, the signal passes through few elements, there is no feedback, Class A operation is continuous, distortion is independant of the load (only the output swing will reduce), and the circuit can to optimised or signal level and performance.
I suggest you try the balanced line stage, I'm sure the effort will be very worth while.
My own experience with the Aleph 5 thus far indicates (with credit to Mr Pass) it delivers where others fail and I expect a similar outcome with the Balanced Line Stage.
regards
macka
* (Please note I am not a Pass salesman , but this would be an enjoyable and rewarding occupation- perhaps in my next reincarnnation)
