This PCI card works out of the box. No problem to switch between this one and the motherboard one.

lspci -vvnnk

03:02.0 Multimedia audio controller [0401]: Ensoniq ES1371/ES1373 / Creative Labs CT2518 [1274:1371] (rev 06)
        Subsystem: Ensoniq Audio PCI 64V/128/5200 / Creative CT4810/CT5803/CT5806 [Sound Blaster PCI] [1274:1371]
        Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=slow >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 32 (3000ns min, 32000ns max)
        Interrupt: pin A routed to IRQ 23
        Region 0: I/O ports at ec00 [size=64]
        Capabilities: [dc] Power Management version 1
                Flags: PMEClk- DSI+ D1- D2+ AuxCurrent=0mA PME(D0+,D1-,D2+,D3hot+,D3cold-)
                Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
        Kernel driver in use: snd_ens1371
        Kernel modules: snd_ens1371