Matching tube pre imdedance to SS amp?

Bought an ATI 1502 amp and running it with Ohm Walsh speakers and a SS preamp from SAE. Interested in running a tube preamp with it but per the manufacturer I need to be careful about "matching the preamp impedance to the amp"? Can anyone translate that? I have a tube pre that I ran with my old SAE power amp and it sounded good. But I may have been what am I looking for to match this up? What happens if they are not matched appropriately?Help?
See my first post in this thread:

-- Al
As a general rule, you want to make sure that the input impedance of the amp is at least ten times the output impedance of the preamp.

Almost all tube preamps (except those with output transformers, of which there are few) have high output impedances in the bass, e.g., 4,000 Ohms, which causes bass rolloff (decreased bass) with some amps. High-end solid-state amps often have input impedances of 100,000 Ohms, so it's not always a problem, but there can be a problem with certain solid-state amps (e.g., classic Rowland, many studio amps).