I own the 352 and have considered and auditioned the 402. The 402 is a 352 with more power and LED lighting. I listened to the 252 but it doesn't have the dual differential output design that the 352 and 402 have, therefore the noise floor is not as quiet. Although the 252 is a great amp I decided to not purchase it yet. The dual differential design is called that for the 402 but in the 352 they had named it double balanced output, but the boys as Mc insured me it is the same path but they wanted a new name for the newer design 402. I would go with the 402 just from the basis of more power, no bulb replacement ( a hassle to avoid if possible) and the 1/2" glass front.