I've had my Kg4 powered by a Yamaha M-65 2-ch amp at one time. Very nice sounding. The amp and speakers. Kg4 are a great bang for the buck. Nice tonal balance, excellent imaging. I've had mine since the 80's and won't sell them. I've even purchased a pair of the poly mid/woof should I need replacements.

The original mid/woof drivers are very hard to find. You see them every so often on ebay, but a good percentage have dust cap wrinkles. I'm not sure why, but it seems to me they have uneven stresses within the driver, so I bypass them. Others I've seen want way too much money.