Mbonn-
I was in your situation not too long ago. I concidered the GNS with the Reference upgrade for my 15 and called Steve at GNS. We spoke at length and he basically said that even with the upgrade, the 15 will not be as good as an LS5 MkII or III. for example and may or may not be the equal of the 25, but wont be "better" than the 25.in his estimation. I ultimately decided to sell the 15 for a MkI 25 with the variable gain of 6,12 or 18db. and put Siemens 7308's ( now British Ediswan CV5358's)) tubes in it. I think this may be a better choice.Better PS regulation and just more pre amp in the 25. In fact, I would seriously think about a used LS5 MKII or III for about the same price. Most will agree this is the superior pre amp sonically. -Ken :)
I was in your situation not too long ago. I concidered the GNS with the Reference upgrade for my 15 and called Steve at GNS. We spoke at length and he basically said that even with the upgrade, the 15 will not be as good as an LS5 MkII or III. for example and may or may not be the equal of the 25, but wont be "better" than the 25.in his estimation. I ultimately decided to sell the 15 for a MkI 25 with the variable gain of 6,12 or 18db. and put Siemens 7308's ( now British Ediswan CV5358's)) tubes in it. I think this may be a better choice.Better PS regulation and just more pre amp in the 25. In fact, I would seriously think about a used LS5 MKII or III for about the same price. Most will agree this is the superior pre amp sonically. -Ken :)