Agaffer, perhaps you are correct as a general rule of thumb. But then there are always excepts to those rules. I own a Primare P30 pre/pro and a Chapter Audio Pre-amp which retails for almost 3 times the price of the P30.
I've also owned and A/B compared the P30 to the Pass Labs X2.5 and X-1 preamps, as well as a fully loaded Placette Active Linestage. In addition, I borrowed a Conrad-Johnson PV14, an Electrocompaniet, and an Ayre k3-x preamp in order to perform some A/B comparisons to the P30.
The Chapter Preface is the pretty clear leader over all the others and the best preamp I've heard to date. But the very highly rated Pass Labs pre-amps just barely surpass the sonics of P30 and the ergonomics of the P30 are better than the Pass Labs units.
As good as the Placette was in the highs, it simply could not provide a balanced or proper weighting in the lower regions like the P30 via it's XLR connections.
The CJ, Electrocompaniet, and highly rated Ayre weren't even in the same league as the P30.
Primare is a little known Swedish company with a music first and minimalist approach. And the P30 provides a 100% TRUE analog processing when in by-pass mode.
Of course there are compromises with the P30 just as with virtually every other product. But the P30's sonic attributes across the frequency spectrum are quite competitive with any one of the preamps I mentioned above and even superior to some of those same.
Yada, I'm not familiar with the sonics of the Lexicon, but I would recommend your considering the following mods to maximize your performance:
1. Disconnect the grounds on all components except for your preamp.
2. Install your preamp (and your other components) on their own dedicated circuits/lines.
3. Install Hubbell cryo-dipped wall outlets, IECs, and plugs. I've only tried one such IEC and the improvements were quite surprising.
4. Consider switching over to XLR for potentially better dynamics.
5. Install Star Sound's Audio Points underneath to transfer vibrations away from the preamp.
6. Install the pre/pro and your other components in a racking system that will follow the same principles as the Audio Points. In other words, coupling or mechanical transfer of air-borne vibrations and resonance to ground.
7. Purchase a Foundation Research LC-1 in-line power conditioner(which is dedicated to one component). Better yet, purchase one for every component.
8. If configuration settings allow, shut down all the Lexicon's text displays and digital processing and set all settings possible to by-pass mode if it provides 100% TRUE analog processing. I use the word TRUE because some to many pre/pro's still convert the signal to digital and then back to analog even when they advertise 100% analog processing. The less the Lexicon does, the less electrical noise the better the potential for sonic improvements.
Hope this helps,