250 TI Classic real impedance

[Latsa]

I use to amplify my 250TI's with an old Sansui Ba-3000 wich doesn't offer the possibility to choose the impedance output. I am now the happy owner :) of a McIntosh combo ( Mc 402 and C46 ).The 250TI classic's are rated at 6 Ohms and the Mc 402 ( with autotransformers ) offers the possibility to choose between 2,4 or 8 Ohms ( not 6 :() so for safety i choosed to use the 4 Ohms output. I would like to give a try with the 8 Ohms output but if the real impedance goes lower then 6 ohms i am affraid it could be hazardous for my brand new McIntosh :banghead:
Does anyone ever tried ?

[10 Watt Street]

The 4 Ohm tap is probably preferred, but there is no harm from using the 8 Ohm tap.