Preamps waste of money?

If your source and amp are a good match, a passive attenuator will work great. If not, a preamp is the correct way to go.
I have a Lightspeed attenuator in my system and love it.

Preamp has many functions other than volume control
- input selector
- balance control (some have tone control)
- impedance matching
- allows use of balanced cables
- breaks ground loops on balanced connections (transformers)
- absolute phase inversion
- some allow to adjust level for each input (Rowland Chorus)
- have unity gain bypass for the theater system
- phono amp for TT
- rumble high pass filter
- remote control
etc.

If you don't need any of it then any stand alone volume control will do. I use Benchmark DAC1 as a preamp with volume control for 3 digital sources with balanced cables to power amp.

Thanks for your opinions on this matter. I hear decreased dynamics using a passive preamp no matter how careful you are about impedance matching and interconnect length (loss of oomph as one of you put it). This was until I placed the stepped attenuator in the input stage of the amp. Going direct from my DAC to amp got rid of the extra interconnect between source and preamp (including all the resistors, caps, wires, switcher, etc in an active preamp), and the dynamics appeared in spades. I literally was startled when I first played music. I really thought I had an active preamp in there, but none of the coloration. My tube DAC actually has 8 kOhm output impedance and my tube amp 100 kOhm input impedance. My SS DAC has output impedance of 50 Ohm. Either way, both macro and micro dynamics are startling. I guess I hit proverbial pot of gold at the end of the rainbow. I can not imagine spending $5k or above for a good active preamp, when I'm getting this kind of result. I've heard a lot of expensive active preamps $15k+, and I don't remember getting this level of transparency, neutrality (more warmth and less thinness, like real life), detailed smoothness, dynamics and soundstaging/imaging. I guess all the stars lined up for me. YMMV.

If the stars lined up for you in this instance then congratulations are in order. I, like many of the respondents on this thread have never heard a good quality active linestage outperformed by a passive or direct source-amp connection configuration.
This set up worked out so I`m happy for you.

To gain absolute purity cred, you need to avoid music recorded by any method other than direct to disc, although ideally music should bypass everything and should only be listened to when performed by naked musicians using acoustic instruments played while they stand on boxes in the open air in a semi circle around your head.