The Diamond series loves more current. Of course it'll sound like ass fart if you drive it with unworthy gears. Go to The Listening Room and ask for a proper audition with a good beefy amp and you'll see what I mean.
I could not agree more. The bookshelf models typically drop below 4 ohms, while the hardest to drive one (the 9.6) drops to the 2 ohm zone (and at the same time gets quite capacitive). Entry level to midlevel AVRs may not have the stiffness to maintain signal integrity when driving such a load. The 9.6 lumbers around sluggishly with no sense of sparkle or impact with the wrong amplifier. A high current solid state amplifier is what I'd recommend with these speakers. It'd take an expensive tube amplifier (or a purpose-built one) to be up to that task.
Most people pair these things with budget AVRs and amplifiers because of the low price, but that could be a recipe for disaster (well, disappointment to be exact). They're among the most current-hungry speakers in this price segment, and that spoils their budget-friendliness (in terms of system cost).
I'm not saying that a good amp will make these speakers blow exotica out of the water, but they will sound appreciably better. The reason why they've gotten good reviews abroad despite the higher prices in those markets is probably because those reviewers had the right gear to match (aside from individual preferences).
For people looking for same-priced speakers for entry level AVRs, there are speakers that don't need much current or grip. The Polk M series for example, is particularly suitable for this application.
