Pre Amps For Line Level Applications.

[Welder]

I understand that for vinyl replay a pre amp or some form of step up device is necessary.
My view has been in the past though, the less electronics on the analogue side of a system the better.
For most digital users, CD or File the only possible benefit that springs to mind of having a pre amp in the system is having a volume control.
For file audio it is possible to run signal directly from Dac to power amp with certain makes and have a computer based application such as the music player controlling the volume; this can even be done remotely with certain players.
So, are there any benefits of having a pre amp in a line level system?

[The Grand Wazoo]

I think it's true to say that for pretty much every person I hear of going over to passive pre-amplification, I hear of another going back to active.

[John]

Having used both active and passive I favour the extra gain offered by this method Remember most phono stages still require the extra gain of the active to sound at their best
Its a shame most manufctures stopped adding phonostages within amps Perhaps a list of amps to look out from the past that have a good built in phono stage
I guess the other part, I wonder is it better to have all that gain outside an amp?

[Welder]

I understand the necessity for pre amps when low level voltages such as a cartridge are used. (I preferred active myself )
I’m rather more interested in whether the extra electronics, cabling etc is worthwhile for line level applications.
A pre amp does offer a lvel of component tuning in such a system but given I’m primarly considering file audio, the bulk of the tuning may possibly in the future be done on the computer leaving the Dac to carry out conversion tasks only.
So if volume can be controlled by the music playing app then what other benefits might a pre amp have in such a system?

[MartinT]

I prefer an active preamp as it drives my power amp (in balanced mode) much better than doing it passively. I did experiment with passive but found that it sucked the life from the music.

Also, beware of computer-based volume adjustment. It does it by manipulating the data and using fewer bits of resolution so that by the time you're listening at low volumes you can hear the distortion setting in. Better to use something like the Caiman DAC with volume control, only you sacrifice remote ability.

[Clive]

It mainly depends on the quality of the output stage of the source. Most opamps on DAC outputs are not up to driving 2 sets of i/cs and a passive attenuator and theu some drop out of class A. It also depends on the power amp. More often that not a good preamp is better but it perfectly possible to design systems to work well passive pre's. A system approach is what's needed. If you look at how Paul Hynes has approached this you'll find he has all the gain in the power amp and uses LDRs for his pre, he's taken a system approach that is not conventional but it works.

[Welder]

I believe digital attenuators on board computer (that do not effect the bit rate) are not far off MartinT which is why I’m enquiring about pre amps.

Yes, there are Dacs with volume controls such as Stans but I won’t be using SPDIF for data transfer preferring the computer releated flexibility of USB and async transfer.

[Welder]

Thanks Clive.

This was what I was more interested in.
I’ve been following the Lightspeed thread with interest.
Hmm, I’ve been looking at the London Gold Mono Power amps with more interest recently having had a bit of a whirl with some T class.
Apparently these can be run with a passive device or none at all.

[Ali Tait]

One benefit of an active pre such as my WAD Pre 2 is that it negates any problems with impedance mismatch, something you can only do with a passive by putting buffers before and after.