This is a good question and one without a simple answer. So much depends on synergy (speaker impedance, damping, room acoustics, volume levels, and just something as elusive as overall tone).
If I were to calculate on the basis of the new MSRP of all the items in my system, speakers would occupy about 20%. There have been times when this number has been greater and others at which it's been lower, and this works as the sweet spot for me.
Bear in mind, this includes an expensive standalone phono stage (Pass XP-15, as my favored MC cartridge is a 100 ohm instead of 470 ohm unit); without that it would be about 30% for speakers, as the IS-1000 has a truly breathtaking built-in unit; a turntable and cartridge; a decent power conditioner (Niagara 1000); and a short run of good cables (all cables top of the line Analysis Plus).
Conventional wisdom runs towards about 40% speakers, 20% source, 20% amplification, 10% power and cables, but there have been times when I simply could not get the most out of a good set of speakers without either a great source of great amp.
As an aside: if you don't use a turntable and simply want a great system to run Roon or other network audio, I think the best bang for the buck is in the now-clearance just about anywhere, discontinued products that Audio Alchemy makes. Those are sensational and astonishing value for money, particularly the DAC/pre, and are an immediate night-and-day step up from the Peachtree units.
