Do I really need a preamp?

Its all about synergy as usual I think. Passives make sense to me if properly mated to suitable sources electronically. That might even be one of the best ways to go if done right, at least from the "purist" point of view, a simple signal path that mates well to gear upstream.

What's not to like?

Mating of active pre-amps, especially tube gear, opens up a similar but different can of electronic mating issues to address. Plus the preamp itself becomes more of a potential sound tweak.

There are so many ways to tweak and do it right. Active/passive, who cares really? Just choose your paradigm and do it right! Passive pre-amps offer a different way to do things. Options are good. Just get it right.

The problem you are usually facing with passive controls is the interconnect cable. An active line stage will usually be less sensitive to the cable. In fact if done right, the active line section will control the cable so well that it will have no sonic effect at all.

Passives OTOH require that one be very careful about the cable. Some passives are lower values, such as 10K, which make them less cable sensitive but then you have the problem that not all sources can drive the 10K properly.

I have presented some of the math about why passives can put you at a disadvantage elsewhere on this site, and the math shows that the quality of the control has nothing to do with it.

This is not to say you can't get a passive to work quite well, just that you do have to be careful and results vary quite a lot. Generally speaking though, it means short cable runs.

'Just get it right' is indeed excellent advice.

Mapman is right with proper mating with passives.

And as I have stated many times.

If you decide to give a 10kohm passive a try, such as the very affordable $49.00 Schitt SYS passive pre. http://schiit.com/products/sys-passive-preamp,
the only proviso to look for to give them a great match are.

1: Interconnect to power amp to be low capacitance (<100pf per foot) which most good quality one are, and 3mts or less long.

2: Tube output sources can be a problem if higher than 1kohm output impedance, solid state sources are normally never a problem.

3: Input impedance of the power amp should be 33kohm or higher, which most are (47kohm being the standard).

If you have these, which 99% of systems are, then you can reap the benefits of the transparency and dynamics that a passive will bring to your system.

Cheers George

George is mostly correct here, just watch out that some solid state amps have a 10K input. 47K is not a standard.

Out of a 4V source, I have heard a Goldpoint resistor type passive preamp sound pretty good into Class A, SS monos with 100K ohm input, but still lacking depth and dynamics compared to the same amps played through my preamp, which is buffered with no gain. Into NC1200 Class D amps, the passive preamp sounds very clean, and delivers close to the same level of dynamics as I achieve through my buffered preamp. However, through my Class AB SS stereo amp with 10K ohm input, the passive preamp sounds terrible.

I also have a pair of balanced Endler attenuators, which connect directly to the amplifiers so there are no cables required after the attenuators. I cannot discern any significant difference in dynamics between those and the Goldpoint passive, from which I use a1M cable into the amps.