         XCTAssertNotNil(outputStream.availablePhysicalFormatsMatchingCurrentNominalSampleRate(true))
         XCTAssertNotNil(outputStream.availablePhysicalFormatsMatchingCurrentNominalSampleRate(false))
 
-        let outVirtualFormat = try XCTUnwrap(outputStream.availableVirtualFormatsMatchingCurrentNominalSampleRate()?.first)
         outputStream.virtualFormat = nil
-        XCTAssertEqual(outputStream.virtualFormat, outVirtualFormat)
+        XCTAssertNotNil(outputStream.virtualFormat)
 
-        let outPhysicalFormat = try XCTUnwrap(outputStream.availablePhysicalFormatsMatchingCurrentNominalSampleRate()?.first)
         outputStream.physicalFormat = nil
-        XCTAssertEqual(outputStream.physicalFormat, outPhysicalFormat)
+        XCTAssertNotNil(outputStream.physicalFormat)
 
         let inputStream = try XCTUnwrap(inputStreams.first)
         XCTAssertTrue(inputStream.active)

        XCTAssertNotNil(inputStream.availablePhysicalFormatsMatchingCurrentNominalSampleRate(true))
        XCTAssertNotNil(inputStream.availablePhysicalFormatsMatchingCurrentNominalSampleRate(false))

        let inVirtualFormat = try XCTUnwrap(inputStream.availableVirtualFormatsMatchingCurrentNominalSampleRate()?.first)
        inputStream.virtualFormat = nil
        XCTAssertEqual(inputStream.virtualFormat, inVirtualFormat)

        let inPhysicalFormat = try XCTUnwrap(inputStream.availablePhysicalFormatsMatchingCurrentNominalSampleRate()?.first)
        inputStream.physicalFormat = nil
        XCTAssertEqual(inputStream.physicalFormat, inPhysicalFormat)
    }

    // MARK: - Private Functions

import XCTest
@testable import AMCoreAudio

class AudioStreamTests: XCTestCase {
    func testProperties() throws {
