The power inserter supplies 21v to the DPP44. The DPP44 in turn, supplies the power to the LNB's. I just un hooked all my DP IRD's and my 2700 still saw all 4 sats. The only restriction for the 2800,3900,4900,6000 as per the instruction's, Was that Sat inputs on the DPP44, 1&2 needed to see 110 or 119, input 3 needs to see 61.5,148,105 or 121. Input 4 need to see 105 or 121. I havent tried to swap inputs to see if there intruction are right or not. It said no restriction for inputs if you have DP IRD's. They also mentioned 1000,2000,3000,4000,5000, jvc d-vhs, 7100, 7200 - it say's any DBS input's on input ports 1,2 and 3 but that port 4 was not supported!