Last time I listened to the Totem Element Fire, it was driven by a little 2X90 NAD integrated amp. It sounded nice and did not give me the impression it needed more power to sound better. The room was small, may be around 12X20 but the NAD was no where near its limit either. I thought (not 100% sure) the Forest is a notch lower. It may be slighly more difficult to drive than the Fire but not to the point that it would make any difference in terms of pairing them with preamp/amps.
For low level input such as from moving coil cartridges the quality of preamps could be critical whereas for high output media such as discs, HD flac files, etc., the preamp should not be that critical as long as it is of decent quality. Power amps on the other hand could have major impact on sound quality but even then as long as you buy from a reputable company such as Rotel, NAD, Bryston, Parasound, Outlaw, Adcom, ATI or even the low cost Emotiva amps you should be fine. The important thing is to buy more than enough power to ensure the amp will always be operating within its design limits.
What you heard about how certain speakers work better with certain amps are not reliable. They are just hearsays probably from people who either have to justify their spendings to feel good or they truly think they heard the "out of this world" kind of sound due to Placebo effect. Amp manufacturers are not going to design their amps to suit just certain speakers. Their design goal should be to produce amps that just amplify the input signals faithfully, i.e. minimum distortions, linear frequency response, high damping factor, adequate power reserve for peaks etc. It is true that some speakers are more demanding but that's about all there is to consider, again I am talking about decent amps such as those mentioned, not just any amps.
Of couse this is just my opinion but I do typically base my opinion on as much known scientific facts as possible. In the audio world today there really isn't much unknowns that could affect sound quality.
