I would upgrade whichever I perceived to be the weekest link first. Aside from that, meaning 'all things being equal', I'd go for the interconnects first for several reasons:
1. Because of the low voltage being passed thru the ic's, they are performing a greater role when dealing with sensitivity. One little design flaw, impedance matching, veiling, constriction, glare, etc., here can go a long way. Assuming the replacement ic is 'better', I believe the ability to hear the sonic differences is potentially greater unless the speaker cable is inferior enough where they prevent you from hearing any improvements.
2. I have a feeling that because of the potential bottlenecking in the ic area due to low voltage sensitivity, etc, it is entirely possible and likely more probably to replace a speaker cable with a clearly superior cable, yet not hear any sonic improvements worth noting because of the restrictions in the inferior interconnect. And I suppose this argument can be used the other way around.
Of course I could be wrong on both counts above.
-IMO
1. Because of the low voltage being passed thru the ic's, they are performing a greater role when dealing with sensitivity. One little design flaw, impedance matching, veiling, constriction, glare, etc., here can go a long way. Assuming the replacement ic is 'better', I believe the ability to hear the sonic differences is potentially greater unless the speaker cable is inferior enough where they prevent you from hearing any improvements.
2. I have a feeling that because of the potential bottlenecking in the ic area due to low voltage sensitivity, etc, it is entirely possible and likely more probably to replace a speaker cable with a clearly superior cable, yet not hear any sonic improvements worth noting because of the restrictions in the inferior interconnect. And I suppose this argument can be used the other way around.
Of course I could be wrong on both counts above.
-IMO