I understand the pain to have to use a 9 channel amp and only use 5, but it is a sad reality that while manufacturers do still offer 5 channels AVRs they don't offer them with much output current capability. It is hard to find the specs for those speakers, if you can believe what's on Audioholic.com:
Their impedance dip to 3.6 ohms, nominal is only 4 ohms and sensitivity is in the mid 80's. So unless you listen to something like 70 dB average 90 dB peak, sitting from
15 feet, any of those still available 5.1 or 7.1 AVRs won't be able to drive your speakers adequately. Also, in order to have pre-out, that allows you to us external power amps should you ever need to, they are simply not found in 5.1 AVRs. Even the 7 channel AVR-X1800H, it only has pre outs for the front left and right channels and are available in the North American version, not the European version.
So, again, if you must stick with 5.1 or 7.1 channel AVRs, you can go with the following:
Denon S670H
Yamaha RX-V4A
But go easy on the volume, and invest $20 on an USB fan to make sure the unit won't overheat when playing certain 5.1 movie contents. Still, I believe most of us who have been in this hobby for a long time, will likely suggest something like the slightly higher models such as the AVR-X3800H, Yamaha RX-A4A, or comparable Pioneee, Onkyo models, and just pretend they are 5 channels (again, I know it would seem like overkill, but if you like your 4 ohm Wharfedale that has dips to 3.2 ohms and have relatively low sensitivity, then you have to understand they are "power hungry", relatively speaking. That's all I can say..
Wharfedale D310 2-way bookshelf speaker
- Sensitivity (2.83v @ 1m): 86dB
- Nominal Impedance: 4Ω (minimum 3.6 Ω)
- Frequency Response (+/-3dB): 65Hz ~ 20kHz
- Dimensions (H x W x D): 26.5 x 15.5 x 22.8 cm
- Weight: 8.8 lbs
Wharfedale D320 2-way bookshelf speaker
- Sensitivity (2.83v @ 1m): 87dB
- Nominal Impedance: 4Ω (minimum 3.8 Ω)
- Frequency Response (+/-3dB): 56Hz ~ 20kHz
- Dimensions (H x W x D): 32.0 x 18.0 x 27.8 cm
- Weight: 13.2 lbs
Wharfedale D330 2.5-way floor-standing speaker
- Sensitivity (2.83v @ 1m): 88dB
- Nominal Impedance: 4Ω (minimum 4.1 Ω)
- Frequency Response (+/-3dB): 40Hz ~ 20kHz
- Dimensions (H x W x D): 96.5 x 20.0 x 33.8 cm
- Weight: 40.1 lbs
Wharfedale D300C 2-way center-channel speaker
- Sensitivity (2.83v @ 1m): 89dB
- Nominal Impedance: 4Ω (minimum 3.8 Ω)
- Frequency Response (+/-3dB): 65Hz ~ 20kHz
- Dimensions (H x W x D): 19.0 x 51.0 x 23.2 cm
- Weight: 17.6 lbs