If you use Bluetooth with S.M.S.L M400, how is the wireless connection?


The marketing materials make this claim: 

    S.M.S.L M400 features lag-free Bluetooth V5.0 connectivity. 
    The latest Bluetooth supports LDAC, APTX / HD, SBC, AAC 
    and the industry's highest specification 24bit / 192kHz UAT format! 

However, in my experience the Bluetooth connectivity is extremely poor. This is the only functionality on the unit that is disappointing. 

The reviews I read all skipped over testing of the Bluetooth. Therefore, I don't know if I simply received a defective unit or if the Bluetooth connectivity is simply this bad on the S.M.S.L M400. 

I tried swapping out the included small Bluetooth antenna for a longer antenna but that actually made it worse. I have a number of different devices that use Bluetooth connectivity, including aptx HD. (All other Bluetooth devices in the area were all turned off during my testing.) The S.M.S.L M400 is by far the worst performing device I have when it comes to Bluetooth connectivity. Even a $25 receiver from Amazon performs better. I also verified the connections were aptx HD and did a number of troubleshooting steps. Bluetooth connectivity on the S.M.S.L M400 is consistently too poor to even use with multiple dropouts, etc.

I'm thinking about exchanging this unit because, given how well every other function performs, I have to wonder if my Bluetooth functionality on this unit is defective. Any opinions?

lowoverdrive
I've had good success with SMSL.Is it possible the source transmitter is the problem?I use Bluetooth on my Burson,which is very similar to the SMSL streaming from an LG G8 & it sounds amazing,with no lag or locking problems..If the source transmitter is up to the level of the SMSL I would say yes try a replacement..
@freediver  - thanks for your reply.

> Is it possible the source transmitter is the problem?
No, I tested it with several other Bluetooth AptX receivers. The only one not working properly is the SMSL M400.

> I would say yes try a replacement..
Thanks for confirming your experience. That's the info I needed to make my decision.