Speaker question Marshall 4210

[ljholland]

I replaced the G12M70 on my 80's 4210 with a Celestion Classic Lead 80. I realized the the original speaker was 16 Ohm ....and the new CL80 is 8 Ohm. Problem? Or only an issue is I also want to pair it with an external cabinet?

(BTW - the CL80 sounds really nice)