Keep them both!! I played 5 string exclusively for over 10 years. I had a huge yearning to go back to a P-Bass. Now all three of my 4 strings (Jackson, P-Bass and Stingray) have Bass extenders. I keep my Jackson extender tuned to drop C. There is no right or wrong. Just play and keep...
I apologize if this has been asked before. I want to use my SWR 210 (8ohm) with my SWR 410 (4 Ohm). These are clearly made to be used together but the combined Ohms equal approximately 2.6 Ohms. My head is rated at 4 Ohms minimum. How can I do this.