Yamaha speakers have typically been very laid back sounding, some have described them as sounding "remote." I once had a pair of Yamaha monitors in my home for a home trial and I confirmed they sounded too laid back for my tastes, but that also could have been the result of not having the right electronics to drive them. I have long campaigned for buyers to carefully match the electronics with the speakers, lest they get a combo that doesn't sound right.
Frankly, for Yamaha speakers, you generally cannot do better than a Yamaha receiver. You have not specified a budget, but I would look into a Yamaha RX-V1400 or higher receiver. The higher end Yamahas have a highly detailed (some would say "bright") sound that is well matched to the sonic charecteristics of the Yamaha speakers. I am not very fond of the lower end Yamahas, but the 1400 or higher are very good and should provide a good match for your speakers. However, don't just buy one. Find a dealer where you can try it out in your home for a weekend and return it if you don't like the sound. A good dealer will let you do this. Then, if you like it, you just keep it. If it doesn't work for your speakers and program material, return it and continue your search--just repost here and let us know what you didn't like about the sound and we can steer you to something your ears will like better.