How important is the amp?


Over the last few year I have upgraded my phono amp (Sensor Prelude), Turntable (SAC Girati Grande) etc.

But I have never upgraded my integrated amp, a Symphonic Line La Musica. At what point do you upgrade your amplifier. I have been looking at a 2nd hand RG10 mk 4 reference or maybe a Kraftwerk.

When I fool around with cable and other items I can still hear improvements. As long as I can still hear changes in my system when I upgrade I think my amp is still fine or is that a wrong train of thought.
mordante
If you really like your speakers and plan on keeping them for some time, then amp upgrade is definitely a right move. You might want to upgrade speaker cables too in this case. Without knowing your speakers and taste in sound and music, I'll just mention Gryphon and Rowland, to add to your list.
However, you said you'd never upgraded your integrated - maybe you like it.
The amp is pretty important, but a lot depends on your speakers. If the speakers are meant to be driven with transistors, its likely you will not hear a lot of difference between amps. But if the speakers are meant to be driven with tube amps, you may hear pretty dramatic differences. Some speakers can be driven by both, then you can compare what the differences are between tubes and transistors and again the differences can be pretty profound.

I would think that good conventional speakers should sound good with both transistor and tube and hybrid amp, just different. Electrostatic, horns etc may be another matter.
10-08-15: Inna
I would think that good conventional speakers should sound good with both transistor and tube and hybrid amp, just different.
Nah! I don't think so. I'm in agreement with Ralph here. if you look at the speaker impedance & phase plots you can tell whether the speaker was meant to be driven by s.s. or by tubes. Also, talking to the speaker manuf can reveal some important info such as what amps do they use when they "voice" their speaker. All this leads to the correct category of amplifier - tube or ss or hybrid, etc.
A speaker driven by the wrong sort of amp can sound terrible...
Mordante,
this is probably a biased view since I'm a big fan of Symphonic Line amps myself. I've had experience with the RG4 Mk3, RG1 & Kraft 300 amps. Symphonic Line amps are really very good & can drive most speakers. So, if it were me, I'd wait till the last minute to upgrade the La Musica amp.
having Said that a friend's friend got the Kraftwerk & found it to be a superb amp. I don't have knowledge of how the La Musica & Kraftwerk amps compare.