After haveing tis now for 7 months this thing is a good preamp I makes my project debute carbon evo as loud as my cd player is and the tube are functional I did buy the extra tubes for it I uavent played around with swapping tubs to see if it sounded diffrent I'm still using the factory tubes it game with over all I would recomend this it's a really good pre amp for the price at a 98db Snr that's really good I recommend it.