As long as the power supply caps meet Krell design specs, you shouldn't have any reason to worry. These are power supply caps, not caps in the audio circuit chain. This is really not a big deal or problem. Power suppy caps can be very expensive, especially if the rail voltages are high. The higher the rail voltage, the more expensive the caps would be. So, they probably saw that one channel was damaged and the power supply caps on that side were questionable. So they replaced the caps on that side. If the other side's caps were okay, then why spend the money to replace them? I would have asked the customer if they wanted me to replace them all, which is probably what Krell's Technician did. The customer may have said no due to the costs. If they are quality caps, you would be hard pressed to hear any difference. Same capacitance rating, same or higher voltage rating and you are good to go. Take a quick look to see how much those suckers costs. Say a 33,000 micro farad cap rated at 100VDC. Go ahead and check.
Enjoy
Enjoy