Considering replacing my Rogue Audio Cronus Magnum with separates.

I would call Clayton for recommendations. 

I think calling the speaker manufacturer is excellent advice

My only concern is that it is built by a small enterprise, namely Don Sachs, so not sure how warranties and repairs work once he retires or worse.

Interesting point of view. My concern has always been that you cannot match the performance of a really good integrated without equally good interconnects, power cords, cones, rack, fuse, etc. and by the time all this is done you have spent way more money to get about the same results as the integrated. If that.

I wouldn't worry about warranties. Herron Audio is in the same situation with Keith Herron. I would think that for every one who frets what if it breaks there are at least one or two who will wish they'd gotten one while they could. Small companies cannot afford to be fixing stuff. Their name is on the face plate, they see it before it goes out the door, and so if they've been around a while with a good reputation then the warranty is the last thing I'd worry about. But then I am very selective and thorough.
For your amp, Raven audio would be on my short list. Ahead of Prima Luna, because as good as it may well be it is made in China. Raven is made in Texas. That's better even than being made in the USA.

Interesting point of view. My concern has always been that you cannot match the performance of a really good integrated without equally good interconnects, power cords, cones, rack, fuse, etc. and by the time all this is done you have spent way more money to get about the same results as the integrated. If that.

My experience is the contrary. I’ve owned a Rogue CMII and it doesn’t take expensive separates or cables to exceed its performance. That goes for many integrateds. The CMII uses decent parts quality here and there but is built to meet a price point. Its volume control is one of the cheapest Alps Pots available.

The assertion that integrateds benefit from shorter signal paths and fewer insertion losses isn’t reality in my experience. The physical proximity of the low-level signals in relation to the power supplies seems a far greater detriment. And an additional pair of cables really doesn’t result in enough insertion loss to be an audible problem. Even a $3K integrated can sound quite a lot better if it allows bypassing of its internal preamp with an outboard unit, even if the outboard component is something like a $500 DAC/preamp combo.

A point to be aware of is that the unbalanced input impedance of the XA30.5 is on the low side (20K per Stereophile’s measurements), and the largest of the three options offered for the output coupling capacitors of the latest Don Sachs custom line stage (1.5 uF) is recommended for use with amps having input impedances of 20K or more. Personally I would not choose a preamp having that kind of marginality. (The impedance of a 1.5 uF capacitor at 20 Hz is about 5.3K, and the impedance of the preceding circuitry will probably raise the overall output impedance to about 6K, which seems far from ideal when driving a 20K load).

I couldn’t find the corresponding specs for the Sachs Model 2 but I wouldn’t be surprised if the same issue would arise with it, or very possibly a worse issue if the output coupling capacitor is smaller than 1.5 uF.

Also, before choosing the Rogue RP-5 I would check with Rogue about its suitability for use with a 20K load, as its 500 ohm specified nominal output impedance could be much higher in the deep bass region.

Good luck. Regards,
-- Al

HI
Don Sachs here. I can use any size output cap the user desires. Just that 1.5 uF is the largest of my favorite oil cap that I can fit in the case. I can easily fit a 3.9 uF Mundorf silver oil or silver gold oil in there or even a larger value. I just prefer the oil cap as it has a more 3D sound and is just more musical than anything else.

Honestly, I have no idea why anyone would design a power amplifier with input impedance less than 47K.  

cheers,
Don