The DM2-2xx is the previous model number of PO-2xx. https://www.cs1.net/products/jensen_transformers/PO-2XX.htm The transformers in PO-2xx use thicker wire windings thus heavier and they don’t have shielding. The transformers in PI-2xx are much smaller and in cylinder shields. The PO-2xx spec is better on paper at zero ohm measurements, but worsen quickly at 150 ohm load or 300 ohm load (curves on Jensen website). Thus in common real world cases, PI-2xx would have better performance. But I don’t have EE background, could not explain the reasons.