If I just use a DAC, do I need a Pre-amp?

Yes you can, but the impedances of the equipment might not match, causing anomalies

There is no impedance match problem with today's solid state sources, but there "can" be with boutique "tube output sources".

Cheers George 

Have tried the following preamp configurations with my Wilson Alexia 2s, Linn Selekt DSM with Katalyst DAC, and Pass Labs X600.8 monos:

1) VTL 6.5 Signature II [tube-SS hybrid] ($18K)
2) McIntosh C2700 [tube] ($8K)
3) Audio Research Reference 6SE [tube] ($17K)
4) NO PREAMP - direct to amp

The Audio Research Ref 6SE for this particular set up was the winner, with all options having unique characteristics that were quite good unto themselves.

But we aim for a natural, warmer sound that encourages long listening sessions and deals well with a broad and eclectic spectrum of musical genres. This translates into us favoring a tube preamp since our amps are solid state.

The direct connect from the Linn Selekt DSM to the amps sounded lethargic just enough that after a few songs we were done listening. Sure, the highs were crystal clear and the bass had punch. But there was inferior cohesiveness between the highs-mids-lows, and the highs were a bit tinny and borderline fatiguing while the bass was not as tight in relation to the rest of the musical frequencies—compared to the tube-based Ref 6SE.

Throwing the Ref 6SE back into the line-up, the musicality returned and we listened for hours, sampling every type of music. We never returned to the direct DSM-to-amp config.

Since we have Pass Labs amps, we are getting in a demo of the XP-32 preamp, which we have heard good and not so good about. But we are checking out the synergy that may arise from both pieces (meaning the preamp and amp, that is, as the XP-32 is a 3 chassis set up and the monos are, well, a 2 piece deal) being from the same manufacturer.

My point: YOU have to listen for yourself. Never let anyone tell you what you will find best. It is YOUR room, YOUR system, YOUR ears and YOUR music. All the electrical theory and bits and bytes mean nothing if you hate it. This is art more than science. You are a living soul, not a robot.

@athrillofhope - Provided pretty much the last word on this.

The only thing I would say is that really good preamps can have an eye watering price tag attached. Even extreme versions of a passive can be as expensive as you feel the need. They can also be really cheap, like the Schiit sys - while decent, you still just get what you pay for. Better volume pots exist, etc. Their Saga+ pre in passive mode with remotely controlled switched resistor network is a better choice. That's what I currently use as a simple attenuator between a Schiit Bifrost II DAC and True Image CM2500 power amplifier.

 

On the fear of missing out...

For those on a shoestring budget like me,who want to play in the big leagues have to learn and build for themselves. The DIY audio community has a great Nelson Pass thread, featuring sporadic postings from Nelson himself who is an avid DIY proponent. After all, if there was no DIY, this hobby would have never bootstrapped.

You can spend the money on a chassis and components where it counts and build your own great pre. Keep your money where it belongs and stop funding someone else’s penchant for lazy days on the back 9.