Are Pre-Amps necessary?

Not when many poweramps use opamps as their balanced inputs, and then it routes to their single ended input.
In these cases by using the single ended input, you get a better sound, as there’s no opamp in the signal path then.

OK George, by this comment I have to assume that opamps are not a thing with which you are familiar. Opamps (operational amplifiers) have very high gain open loop. Their gain structure is thus defined by the feedback resistance vs the input resistance. When both values are the same the opamp has unity gain. This is a lot of feedback, and most opamps today can support that amount of feedback such that at any frequency in the audio band they will be entirely neutral.


And unity gain is how such at thing would be set up, since the amplifier in question would have no need of additional gain when using the balanced input. At any rate, if the designer did execute the opamp input in a substandard manner (and I have seen that), such a thing does not reflect on balanced operation nearly so much as it does on that designer!


Take this from someone who made their career in tube electronics, OK?

So the sound quality will be unaffected although I do concede that using an opamp solely for this purpose is a poor execution of the amplifier design; better if the amp simply has differential inputs used for either balanced or single-ended operation (and many in high end do exactly that). McCormick and Pass Labs being two examples off the top of my head...

vanson1

Are Pre-Amps necessary?

With all the advances in digital sources, do we still need a $5,000 pre-amp?

All we need is a switching device and maybe a Phono preamp/RIAA curve device.

Preamps are a dinosaur left over from the phono days, when sources had very low outputs and far higher output impedances.
They are not needed these days with nearly all of todays sources, except maybe with weak tube output sources.

As I and many others say, in nearly all cases they are worse than going direct or using a passive, and a waste of big money for the higher end ones.
https://forum.audiogon.com/posts/2262469

Cheers George

They are not needed these days with nearly all of todays sources, except maybe with weak tube output sources.

Sheesh. It was nice when george was off. Now we have rehash this again and again. Tape is still very much with high end audio as is the LP. These media are not served by any DAC I know of. Plus there are active line stages that have better volume controls than I'm used to seeing in DACs. Line stages first started showing up in the early 1990s when the idea of an all-digital system became a thing. Rather than a relic, it seems as if they are not going away anytime soon.


If you are going to run a passive control, the best place for it is built into the power amplifier. That way the impedances involved can be far better controlled. But if you have monoblocks it gets tricky.


My front end with preamp has 30 feet of interconnect between the amps and the output of the preamp, which also drives a subwoofer amplifier. In this way I keep the front end of the system at a lower level of vibration and I can run a Distributed Bass Array. These are the sort of things you can't do with a passive control. At best, to make those work you have to run short cables- 30 feet is out of the question. If you need dual outputs, you'll instantly be in trouble, and if you want to be finally rid of that pesky standing wave in your room (causing a loss of bass at the listening chair), you'll need a distributed bass array to do it.

Your the one who reacted (very defensively) to my comments first, where I was just agreeing with two other members that had nothing to do with you

Sheesh. It was nice when george was off.

+1