There are a couple of issues at work.
First, many of the NOS tubes were made in factories that no longer exist, using machines long since gone. For tubes commonly used in audio equipment there are few to none made in the US, Britain or Germany anymore. Some feel the modern factories in Russia, China and other countries just don't turn out quite the same product.
Second, there is the rarity factor. As NOS tubes are put into use they don't get replaced. With any "luxury" item (and fine audio equipment does fit in that category), an increasingly dwindling supply of irreplaceable parts certainly lends a certain cache to the old stuff even if one argues the new production is just as good.
Consider yourself lucky that you like the stock tubes best as it just makes your life easier and less expensive.
First, many of the NOS tubes were made in factories that no longer exist, using machines long since gone. For tubes commonly used in audio equipment there are few to none made in the US, Britain or Germany anymore. Some feel the modern factories in Russia, China and other countries just don't turn out quite the same product.
Second, there is the rarity factor. As NOS tubes are put into use they don't get replaced. With any "luxury" item (and fine audio equipment does fit in that category), an increasingly dwindling supply of irreplaceable parts certainly lends a certain cache to the old stuff even if one argues the new production is just as good.
Consider yourself lucky that you like the stock tubes best as it just makes your life easier and less expensive.
